Inter-RAT (radio access technology) reestablishment enhancements in multi-RAT dual connectivity (MR-DC)

ABSTRACT

Embodiments include methods for a target node to establish a connection with a user equipment (UE) operating in dual connectivity (DC) with a PCell utilizing a first radio access technology (RAT) and with a PSCell utilizing a second RAT. Embodiments include receiving, from the UE, a re-establishment request message comprising parameters associated with the PSCell, a first message authentication code (MAC), and an indication of the UE&#39;s selection of a target cell served by the target node as a replacement for the PCell. The target cell utilizes the second RAT. Embodiments include verifying the message integrity based on the first MAC, and determining a full UE context based on the plurality of parameters associated with the PSCell and on a successful verification of the message integrity. Embodiments include establishing a connection with the UE based on the full UE context, whereby the target cell serves as a PCell for DC.

TECHNICAL FIELD

The present application relates generally to the field of wireless communication networks, and more specifically to devices, methods, and computer-readable media that facilitate simultaneous connectivity of a device or user equipment (UE) to multiple nodes in a radio access network (RAN).

BACKGROUND

Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features, and advantages of the enclosed embodiments will be apparent from the following description.

Long Term Evolution (LTE) is an umbrella term for so-called fourth-generation (4G) radio access technologies developed within the Third-Generation Partnership Project (3GPP) and initially standardized in Releases 8 and 9, also known as Evolved UTRAN (E-UTRAN). LTE is targeted at various licensed frequency bands and is accompanied by improvements to non-radio aspects commonly referred to as System Architecture Evolution (SAE), which includes Evolved Packet Core (EPC) network. LTE continues to evolve through subsequent releases that are developed according to standards-setting processes with 3GPP and its working groups (WGs), including the Radio Access Network (RAN) WG, and sub-working groups (e.g., RAN1, RAN2, etc.).

In LTE, the Radio Resource Control (RRC) protocol is used to configure, setup, and maintain the radio connection between the user equipment (UE) and the base station, known as the evolved Node B (eNB). When the UE receives an RRC message from the eNB, it will apply the configuration (also referred to herein as “compile the configuration”), and if this succeeds the UE generates an RRC complete message that indicates the transaction ID of the message that triggered this response.

Since LTE Release 8, three Signaling Radio Bearers (SRBs), namely SRB0, SRB1 and SRB2 have been available for the transport of RRC and Non Access Stratum (NAS) messages between the UE and eNB. A new SRB, known as SRB1bis, was also introduced in rel-13 for supporting DoNAS (Data Over NAS) in NB-IoT.

SRB0 carries RRC messages using the CCCH logical channel, and it is used for handling RRC connection setup, resume, and re-establishment. Once the UE is connected to the eNB (i.e., RRC connection setup or RRC connection reestablishment resume has succeeded), SRB1 is used for handling further RRC messages (which may include a piggybacked NAS message) and NAS messages, prior to the establishment of SRB2, all using DCCH logical channel. SRB2 is used for RRC messages such as logged measurement information, as well as for NAS messages, all using DCCH. SRB2 has a lower priority than SRB1, because logged measurement information and NAS messages can be lengthy and could cause the blocking of more urgent and smaller SRB1 messages. SRB2 is always configured by E-UTRAN after security activation.

A dual connectivity framework has been defined in LTE Release 12. Dual connectivity (or DC) refers to a mode of operation in which a UE, in RRC_CONNECTED state, consumes radio resources provided by at least two different network points connected to one another with a non-ideal backhaul. In the LTE standards, these two network points may be referred to as a “Master eNB” (MeNB) and a “Secondary eNB” (SeNB). More generally, they can be referred to as a master node (MN) and a secondary node (SN). DC can be viewed as a special case of carrier aggregation (CA), where the aggregated carriers, or cells, are provided by network nodes that are physically separated from one another and that are not connected to one another through a fast, quality, connection.

More specifically, in DC, the UE is configured with a Master Cell Group (MCG) and a Secondary Cell Group (SCG). A Cell Group (CG) is a group of serving cells associated with either the MeNB or the SeNB(s). MCG and SCG are defined as follows:

-   -   The Master Cell Group (MCG) is a group of serving cells         associated with the MeNB, comprising a primary cell (PCell) and         optionally one or more secondary cells (SCells).     -   A Secondary Cell Group (SCG) is a group of serving cells         associated with the SeNB comprising a Primary SCell (pSCell) and         optionally one or more SCells.

Put another way, a UE in DC maintains simultaneous connections to anchor and booster nodes, where the anchor node is also referred to as the MeNB and the booster nodes are also referred to as SeNBs. As its name implies, the MeNB terminates the control plane connection towards the UE and, as such, is the controlling node of the UE, including handovers to and from SeNBs. For example, the MeNB is the eNB that terminates at least the S1-MME connection, i.e., the connection between the eNB and the Mobility Management Entity (MME) for the UE. An SeNB is an eNB that is providing additional radio resources (e.g., bearers) for the UE but that is not the MeNB. Types of radio resource bearers include MCG bearers, SCG bearers, and split bearers.

RRC connection with the UE is handled only by the MeNB and, accordingly, SRBs (Signaling Radio Bearers) are always configured as MCG bearer type and therefore only use the radio resources of the MN. However, the MeNB can also configure the UE based on input from the SeNB and hence the SeNB can also indirectly control the UE. In an LTE-DC configuration, the MeNB is connected to the SeNBs via the Xn interface, which is currently selected to be the same as the X2 interface between the two eNBs.

According to LTE principles, UEs provide measurement reports—whether due to event trigger or a periodic trigger—comprising measurements of serving cell(s). For mobility measurements, MeNBs configure UEs according to various criteria including, e.g., frequency to measure, how to report, etc. Correspondingly, the UE sends measurement results to MeNB once the measurement criteria are met. When the UE needs to send a measurement report, whether event triggered or periodic triggered, the UE should always send measurement results of serving cell to network. For UE in LTE-DC, serving cell means both cells in MCG (MN) and cell in SCG (SN).

FIG. 1 illustrates various exemplary LTE DC scenarios involving UEs 110 and base stations (eNBs) 120. As shown, only one SeNB (at most) is connected to any of the illustrated UEs. However, more than one SeNB can serve a UE in general. Moreover, only one cell each from both MeNB and SeNB are shown to be serving the UE, however more than one cells can serve the UE in practice from both MeNB and SeNB. From the figure, it should also be clear that dual connectivity is a UE-specific feature and that a given network node (or a serving cell) can support a dual-connected UE and a legacy UE at the same time. In other words, MeNB and SeNB are roles played, or functions provided, by eNBs 120 for a given situation. Thus, while the eNBs 120 in FIG. 1 are labeled “MeNB” and “SeNB,” this indicates only that they are playing this role for at least one UE 110. Indeed, a given eNB 120 may be an MeNB for one UE 110 while being an SeNB for another UE.

The master/anchor and secondary/booster roles are defined from a UE's point of view, which means that a node (or cell) that acts as an anchor to one UE may act as booster to another UE. Likewise, although a given UE in a DC scenario reads system information from the anchor node (or cell), a node (or cell) acting as a booster to one UE may or may not distribute system information to another UE. Furthermore, in LTE, only inter-frequency DC is supported (i.e., the MCG and SCG must use different carrier frequencies).

In summary, LTE DC allows an LTE-capable UE to be connected to two nodes—MeNB and SeNB—to receive data from both nodes and thereby increase its data rate. The MeNB (or MN) provides system information, terminates the control plane, and can terminate the user plane. An SeNB (or SN), on the other hand, terminates only the user plane. This UP aggregation achieves benefits such as increasing the per user throughput for users that have good channel conditions and the capability of receiving and transmitting at higher data rates than can be supported by a single node, even without a low-latency backhaul/network connection between the MeNB and SeNB.

In 3GPP, a study item on a new radio interface for 5G has recently been completed and 3GPP is proceeding to standardize the new radio interface, often abbreviated by NR (New Radio). At a minimum, NR can be deployed independently without any interworking with LTE, a mode that can be referred to as NR stand-alone (SA) operation. In this mode, a NR base station (called “gNB”) can be connected to a 5G core network (5GC), and an LTE eNB can be connected to an EPC with no interconnection between them.

FIG. 2 illustrates a high-level view of an exemplary 5G network architecture, consisting of a Next Generation RAN (NG-RAN) 299 and a 5G Core (5GC) 298. NG-RAN 299 can include one or more gNodeB's (gNBs) connected to the 5GC via one or more NG interfaces, such as gNBs 200, 250 connected via interfaces 202, 252, respectively. More specifically, gNBs 200, 250 can be connected to one or more Access and Mobility Management Functions (AMF) in the 5GC 298 via respective NG-C interfaces. Similarly, gNBs 200, 250 can be connected to one or more User Plane Functions (UPFs) in 5GC 298 via respective NG-U interfaces.

Although not shown, in some deployments 5GC 298 can be replaced by an Evolved Packet Core (EPC), which conventionally has been used together with LTE E-UTRAN. In such deployments, gNBs 200, 250 can connect to one or more Mobility Management Entities (MMEs) in EPC 298 via respective S1-C interfaces. Similarly, gNBs 200, 250 can connect to one or more Serving Gateways (SGWs) in EPC via respective NG-U interfaces.

In addition, the gNBs can be connected to each other via one or more Xn interfaces, such as Xn interface 240 between gNBs 200 and 250. The radio technology for the NG-RAN is often referred to as “New Radio” (NR). With respect the NR interface to UEs, each of the gNBs can support frequency division duplexing (FDD), time division duplexing (TDD), or a combination thereof.

NG-RAN 299 is layered into a Radio Network Layer (RNL) and a Transport Network Layer (TNL). The NG-RAN architecture, i.e., the NG-RAN logical nodes and interfaces between them, is defined as part of the RNL. For each NG-RAN interface (NG, Xn, F1) the related TNL protocol and the functionality are specified. The TNL provides services for user plane transport and signaling transport. In some exemplary configurations, each gNB is connected to all 5GC nodes within an “AMF Region” which is defined in 3GPP TS 23.501. If security protection for CP and UP data on TNL of NG-RAN interfaces is supported, NDS/IP (3GPP TS 33.401) shall be applied.

The NG RAN logical nodes shown in FIG. 2 (and described in 3GPP TS 38.401 and 3GPP TR 38.801) include a Central Unit (CU or gNB-CU) and one or more Distributed Units (DU or gNB-DU). For example, gNB 200 includes gNB-CU 210 and gNB-DUs 220 and 230. CUs (e.g., gNB-CU 210) are logical nodes that host higher-layer protocols and perform various gNB functions such controlling the operation of DUs. A DU (e.g., gNB-DUs 220, 230) is a decentralized logical node that hosts lower layer protocols and can include, depending on the functional split option, various subsets of the gNB functions. As such, each of the CUs and DUs can include various circuitry needed to perform their respective functions, including processing circuitry, transceiver circuitry (e.g., for communication), and power supply circuitry. Moreover, the terms “central unit” and “centralized unit” are used interchangeably herein, as are the terms “distributed unit” and “decentralized unit.”

A gNB-CU connects to one or more gNB-DUs over respective F1 logical interfaces, such as interfaces 222 and 232 shown in FIG. 2 . However, a gNB-DU can be connected to only a single gNB-CU. The gNB-CU and connected gNB-DU(s) are only visible to other gNBs and the 5GC as a gNB. In other words, the F1 interface is not visible beyond gNB-CU. Furthermore, the F1 interface between the gNB-CU and gNB-DU is specified and/or based on the following general principles:

-   -   F1 is an open interface;     -   F1 supports the exchange of signaling information between         respective endpoints, as well as data transmission to the         respective endpoints;     -   from a logical standpoint, F1 is a point-to-point interface         between the endpoints (even in the absence of a physical direct         connection between the endpoints);     -   F1 supports control plane (CP) and user plane (UP) separation,         such that a gNB-CU may be separated in CP and UP;     -   F1 separates Radio Network Layer (RNL) and Transport Network         Layer (TNL);     -   F1 enables exchange of user equipment (UE) associated         information and non-UE associated information;     -   F1 is defined to be future proof with respect to new         requirements, services, and functions;     -   A gNB terminates X2, Xn, NG and S1-U interfaces and, for the F1         interface between DU and CU, utilizes the F1 application part         protocol (F1-AP) which is defined in 3GPP TS 38.473.

Furthermore, a CU can host protocols such as RRC and PDCP, while a DU can host protocols such as RLC, MAC and PHY. Other variants of protocol distributions between CU and DU can exist, however, such as hosting the RRC, PDCP and part of the RLC protocol in the CU (e.g., Automatic Retransmission Request (ARQ) function), while hosting the remaining parts of the RLC protocol in the DU, together with MAC and PHY. In some embodiments, the CU can host RRC and PDCP, where PDCP is assumed to handle both UP traffic and CP traffic. Nevertheless, other exemplary embodiments may utilize other protocol splits that by hosting certain protocols in the CU and certain others in the DU. Exemplary embodiments can also locate centralized control plane protocols (e.g., PDCP-C and RRC) in a different CU with respect to the centralized user plane protocols (e.g., PDCP-U).

It has also been agreed in 3GPP RAN3 Working Group (WG) to support a separation of gNB-CU into a CU-CP function (including RRC and PDCP for signaling radio bearers) and CU-UP function (including PDCP for user plane). The CU-CP and CU-UP functions can communicate with each other using the E1-AP protocol over the E1 interface. In addition to the new E1 interface, the F1 interface can be logically separated into CP (F1-C) and UP (F1-U) functionalities. Furthermore, according to 3GPP TR 38.806, each of the CU-CP and CU-UP functions can be centralized or distributed independent of the other.

Returning to the above discussion about dual connectivity (DC), 3GPP TR 38.804 describes various exemplary DC scenarios or configurations where the MN and SN can apply either NR, LTE or both. The following terminology is used to describe these exemplary DC scenarios or configurations:

-   -   DC: LTE DC (i.e., both MN and SN employ LTE, as discussed         above);     -   EN-DC: LTE-NR DC where MN (eNB) employs LTE and SN (gNB) employs         NR;     -   NGEN-DC: LTE-NR dual connectivity where a UE is connected to one         ng-eNB that acts as a MN and one gNB that acts as a SN. The         ng-eNB is connected to the 5GC and the gNB is connected to the         ng-eNB via the Xn interface.     -   NE-DC: LTE-NR dual connectivity where a UE is connected to one         gNB that acts as a MN and one ng-eNB that acts as a SN. The gNB         is connected to 5GC and the ng-eNB is connected to the gNB via         the Xn interface.     -   NR-DC (or NR-NR DC): both MN and SN employ NR.     -   MR-DC (multi-RAT DC): a generalization of the Intra-E-UTRA Dual         Connectivity (DC) described in TS 36.300, where a multiple Rx/Tx         UE may be configured to utilize resources provided by two         different nodes connected via non-ideal backhaul, one providing         E-UTRA access and the other one providing NR access. One node         acts as the MN and the other as the SN. The MN and SN are         connected via a network interface and at least the MN is         connected to the core network. EN-DC, NE-DC, and NGEN-DC are         different example cases of MR-DC.

Since deployment and/or migration for these options may differ for different operators, it is possible to have deployments with multiple options in parallel in the same network. In combination with LTE/NR DC solutions, it is also possible to support CA (Carrier Aggregation) in each cell group (i.e., MCG and SCG) and DC between nodes on same RAT (e.g., NR-NR DC). For the NR cells, a consequence of these different deployments is the co-existence of NR cells supporting SA only, NSA only, or both SA and NSA.

In NR or LTE, if a UE in RRC_CONNECTED detects radio link failure (RLF) on the master cell group (MCG) or declares a handover failure (reconfiguration with sync in NR, triggered upon the expiry of the timer T304), the UE selects a ‘suitable cell’ and initiates an RRC reestablishment. A “suitable cell” is defined in 3GPP TS 36.300 and 38.300 as one for which the measured cell attributes satisfy the cell selection criteria; the cell PLMN is the selected PLMN, registered or an equivalent PLMN; the cell is not barred or reserved and the cell is not part of a tracking area which is in the list of “forbidden tracking areas for roaming”.

Although existing RRC re-establishment procedures are sufficient for single-connectivity operation in either LTE or NR, there are various problems related to performing re-establishment in dual-connectivity configuration, particularly with respect to multi-RAT NE-DC and NGEN-DC configurations.

SUMMARY

Exemplary embodiments disclosed herein address these and other problems, issues, and/or drawbacks of existing solutions by providing flexible and efficient techniques for a network to re-establish a target cell, of a second RAT, as a replacement for the UE's current primary cell (PCell) of a first RAT, when the UE is operating in MR-DC. Such embodiments improve both UE and network performance as compared to existing solutions, which require the UE to transition to RRC_IDLE mode and establish the connection from scratch for target cell of the second RAT.

Exemplary embodiments include methods and/or procedures for establishing a connection with a UE operating in dual connectivity (DC) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN), and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN). These exemplary methods and/or procedures can be implemented by a target node (e.g., eNB, gNB, ng-eNB, or components thereof) with respect to the UE.

The exemplary method and/or procedure can include receiving, from the UE, a re-establishment request message comprising a plurality of parameters associated with the PSCell, a first message authentication code (MAC), and an indication of the UE's selection of a target cell served by the network node as a replacement for the PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell and the target cell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA).

In some embodiments, the MAC included in the re-establishment request message is based on a plurality of parameters associated with the PSCell and on an identifier of the target cell. In some embodiments, the plurality of parameters associated with the PSCell can include an identifier of the PSCell, an identifier of the UE in relation to the PSCell, and integrity protection information associated with the SN.

The exemplary method and/or procedure can also include verifying the integrity of the re-establishment request message based on the first MAC. The exemplary method and/or procedure can also include determining a full UE context for the UE based on the plurality of parameters associated with the PSCell, and on a successful verification of the integrity of the re-establishment request message.

Other exemplary embodiments include methods and/or procedures performed by a user equipment (UE) operating in dual connectivity (DC) in a radio access network (RAN) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN) and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN).

These exemplary methods and/or procedures can include detecting a failure associated with the PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA). The exemplary method and/or procedure can also include selecting a target cell served by a target node as a replacement for the PCell. For example, the target cell can utilize the second RAT, i.e., the same RAT as the UE's current PSCell.

In some embodiments, the exemplary method and/or procedure can also include, based on determining that the target cell does not meet at least one of a set of conditions, transitioning to idle mode and sending a connection setup request message to the target node. The set of conditions can include the target cell being from: the same RAT as the SN, the same RAT as the MN, the same Core Network (CN) type as the MN, or the same CN type as the SN.

The exemplary method and/or procedure can also include calculating a message authentication code (MAC) for a re-establishment request message based on a plurality of parameters associated with the PSCell. In some embodiments, the plurality of parameters associated with the PSCell can include an identifier of the PSCell, and an identifier of the UE in relation to the PSCell. In some embodiments, the calculation of the MAC can be further based on an identifier of the target cell.

The exemplary method and/or procedure can also include sending, to the target node, a re-establishment request message comprising the plurality of parameters associated with the PSCell, the calculated MAC, and an indication of the UE's selection of the target cell as a replacement for the PCell. In some embodiments, the exemplary method and/or procedure can also include establishing a connection with the target node, whereby the target cell served by the target node will serve as a PCell for DC.

Other exemplary embodiments include methods and/or procedures performed by a secondary node (SN), in a radio access network (RAN), that is operating in dual connectivity (DC) toward a user equipment (UE) together with a master node (MN) serving the UE's current primary cell (PCell) that is part of a master cell group (MCG), according to various exemplary embodiments of the present disclosure. These exemplary methods and/or procedures can be implemented by a network node (e.g., eNB, gNB, ng-eNB, or components thereof) serving the UE's current primary secondary cell (PSCell) that is part of a secondary cell group (SCG).

These exemplary methods and/or procedures can include receiving, from a target node in the RAN, a context request message pertaining to the UE. The context request message can include a plurality of parameters associated with the UE's current PSCell, a first message authentication code (MAC), and an identifier of a target cell, served by the target node, that was selected by the UE as replacement for the UE's current PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell and the target cell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA).

The exemplary method and/or procedure can also include, based on the plurality of parameters associated with the UE's current PS Cell, providing the target node with a full UE context for the UE. In some embodiments, these operations can include retrieving a UE context associated with the SN based on the plurality of parameters associated with the UE's current PSCell; and sending, to the MN, a request to provide the full UE context to the target node, wherein the request for the full UE context includes the identifier of the target cell served by the target node.

Other exemplary embodiments include network nodes (e.g., base stations, nodes, eNBs, gNBs, ng-eNBs, CUs, DUs, MNs, SNs, etc. of components thereof) or user equipment (UEs, e.g., wireless devices) configured to perform operations corresponding to any of the exemplary methods and/or procedures described herein. Other exemplary embodiments include non-transitory, computer-readable media storing program instructions that, when executed by processing circuitry comprising such network nodes or UEs, configure such apparatus to perform operations corresponding to any of the exemplary methods and/or procedures described herein.

These and other objects, features, and advantages of exemplary embodiments of the present disclosure will become apparent upon reading the following Detailed Description in view of the Drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high-level network diagram illustrating various exemplary Long-Term Evolution (LTE) dual connectivity (DC) scenarios involving user equipment (UEs) and evolved NodeBs (eNBs).

FIG. 2 illustrates a high-level view of an exemplary 5G network architecture.

FIG. 3 is a block diagram showing a high-level comparison of the EN-DC, NE-DC, and NGEN-DC options.

FIG. 4 shows various options for deploying a 5G network with or without interworking with existing LTE and Evolved Packet Core (EPC) networks, according to to current 3GPP standards.

FIG. 5 is a signaling flow diagram for a successful LTE radio resource control (RRC) connection re-establishment procedure.

FIGS. 6A-6C show exemplary ASN.1 data structures for an LTE RRCConnectionReestablishmentRequest message and various information elements (IEs) included therein.

FIGS. 7A-7B show signaling flow diagrams for various NR RRC Reestablishment procedures.

FIGS. 8A-8C show exemplary ASN.1 data structures for an NR RRCReestablishmentRequest message and various IEs included therein.

FIGS. 9A-9E show structures of various other inter-node messages and IEs used during an NR RRC Reestablishment procedure.

FIG. 10 , which includes FIGS. 10A and 10B, illustrates two scenarios in which a UE selects a PCell of a different RAT than the PCell on which the failure occurred.

FIG. 11 , which includes FIGS. 11A and 11B, illustrates the same two scenarios shown in FIG. 10 but with improvements according to various exemplary embodiments of the present disclosure.

FIG. 12 shows a signal flow diagram for inter-RAT reestablishment from NE-DC, where the target MN is the source SN, according to various exemplary embodiments of the present disclosure.

FIGS. 13-14 show signal flow diagrams for inter-RAT reestablishment from NE-DC and NGEN-DC, respectively, where the target MN is different from the source SN, according to various exemplary embodiments of the present disclosure.

FIG. 15 shows an exemplary RETRIEVE MN UE CONTEXT REQUEST message, according to various embodiments of the present disclosure.

FIG. 16 is a flow diagram illustrating exemplary methods and/or procedures performed by a target node in a radio access network (RAN), according to various exemplary embodiments of the present disclosure.

FIG. 17 is a flow diagram illustrating exemplary methods and/or procedures performed by a UE, according to various exemplary embodiments of the present disclosure.

FIG. 18 is a flow diagram illustrating exemplary methods and/or procedures performed by a secondary node in a RAN, according to various exemplary embodiments of the present disclosure.

FIG. 19 illustrates an exemplary wireless network, according to various exemplary embodiments of the present disclosure.

FIG. 20 illustrates an exemplary UE, according to various exemplary embodiments of the present disclosure.

FIG. 21 is a block diagram illustrating an exemplary virtualization environment usable for implementing various exemplary embodiments of the present disclosure.

FIGS. 22-23 are block diagrams of various exemplary communication systems and/or networks, according to various exemplary embodiments of the present disclosure.

FIGS. 24-27 are flow diagrams illustrating various exemplary methods and/or procedures implemented in a communication system, according to various exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. Furthermore, the following terms are used throughout the description given below:

-   -   Radio Node: As used herein, a “radio node” can be either a         “radio access node” or a “wireless device.”     -   Radio Access Node: As used herein, a “radio access node” (or         “radio network node”) can be any node in a radio access network         (RAN) of a cellular communications network that operates to         wirelessly transmit and/or receive signals. Some examples of a         radio access node include, but are not limited to, a base         station (e.g., a New Radio (NR) base station (gNB) in a 3GPP         Fifth Generation (5G) NR network or an enhanced or evolved Node         B (eNB) in a 3GPP LTE network), a high-power or macro base         station, a low-power base station (e.g., a micro base station, a         pico base station, a home eNB, or the like), integrated access         backhaul (IAB) node, and a relay node.     -   Core Network Node: As used herein, a “core network node” is any         type of node in a core network. Some examples of a core network         node include, e.g., a Mobility Management Entity (MME), a Packet         Data Network Gateway (P-GW), a Service Capability Exposure         Function (SCEF), or the like.     -   Wireless Device: As used herein, a “wireless device” (or “WD”         for short) is any type of device that has access to (i.e., is         served by) a cellular communications network by communicate         wirelessly with network nodes and/or other wireless devices.         Unless otherwise noted, the term “wireless device” is used         interchangeably herein with “user equipment” (or “UE” for         short). Some examples of a wireless device include, but are not         limited to, a UE in a 3GPP network and a Machine Type         Communication (MTC) device. Communicating wirelessly can involve         transmitting and/or receiving wireless signals using         electromagnetic waves, radio waves, infrared waves, and/or other         types of signals suitable for conveying information through air.     -   Network Node: As used herein, a “network node” is any node that         is either part of the radio access network or the core network         of a cellular communications network. Functionally, a network         node is equipment capable, configured, arranged, and/or operable         to communicate directly or indirectly with a wireless device         and/or with other network nodes or equipment in the cellular         communications network, to enable and/or provide wireless access         to the wireless device, and/or to perform other functions (e.g.,         administration) in the cellular communications network.

Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system. Furthermore, although the term “cell” is used herein, it should be understood that (particularly with respect to 5G NR) beams may be used instead of cells and, as such, concepts described herein apply equally to both cells and beams.

In the following, the terms eNB (eNodeB), gNB (gNodeB), MCG (Master Cell Group) and Primary Cell (PCell) may be used interchangeably to refer to the node or cell which the UE is connected to in single connectivity. Likewise, the terms SN (secondary node), SeNB (Secondary eNodeB), SgNB (Secondary gNodeB), SCG (Secondary Cell Group), and PSCell (Primary Secondary Cell) may be used interchangeably to refer to the secondary node or cell that the UE is connected to when the UE is configured with MR-DC.

In addition, the terms “source” and “Last serving”, as applied to nodes or cells (e.g., MeNB, MgNB, SeNB, SgNB, MCG, SCG, PCell, PSCell, etc.), can refer to the node or cell to which the UE was connected prior to a failure and an initiation of a reestablishment procedure. Similarly, the term target, as applied to nodes or cells (e.g., eNB, gNB, MCG, PCell, etc.) can refer to the node or cell in which the UE attempts to reestablish a connection. Furthermore, unless otherwise noted, the target (master) node/cell and the source secondary node/cell are intra-RAT and intra-system. In other words, they employ the same RAT and are connected to the same core network.

As mentioned above, although the currently-defined LTE and NR re-establishment procedures are sufficient for single-connectivity operation in either LTE or NR, there are various issues, drawbacks, and/or problems related to performing re-establishment in dual-connectivity configurations, particularly with respect to NE-DC and NGEN-DC configurations. These are discussed in more detail below.

FIG. 3 is a block diagram showing a high-level comparison of the EN-DC, NE-DC, and NGEN-DC options briefly mentioned above. In EN-DC (A), the NR en-gNB (SN) is operating in NSA mode and has no direct control-plane (CP) interface with the EPC. In NE-DC (B), the gNB MN has a direct interface with the 5GC while LTE SN's CP connection is via the MN (e.g., over the Xn interface). The NGEN-DC (C) scenario is similar to EN-DC (A), except that the ng-eNB CP connection is to 5GC via NG-C interface instead of to EPC via S1-C interface. Although not shown in FIG. 3 , the NR-NR DC control plane is still undergoing standardization. As such, it is possible that it could resemble LTE DC (i.e., UE has only one RRC terminated at the MN) or EN-DC (i.e., UE has two RRC terminations, one at the MN and another at the SN).

FIG. 4 illustrates various options for deploying a 5G network with or without interworking with existing LTE and EPC, according to current 3GPP standards. Option 1 depicts the legacy LTE standalone (SA) deployment where LTE eNBs are connected to an EPC. Option 2 depicts NR SA deployment where the NR gNBs are connected to a 5GC. Option 3/3A/3X depicts EN-DC, described above. Option 4/4A depicts NE-DC, described above. Option 5 depicts a hybrid solution where enhanced LTE (eLTE) eNBs (e.g., ng-eNBs) are connected to a 5GC. Finally, option 7/7A depicts NGEN-DC, described above.

In NR or LTE, if a UE in RRC_CONNECTED detects radio link failure (RLF) on the master cell group (MCG) or declares a handover failure (reconfiguration with sync in NR, triggered upon the expiry of the timer T304), the UE selects a “suitable cell” and initiates an RRC reestablishment. A “suitable cell” is defined in 3GPP TS 36.300 and 38.300 as one for which the measured cell attributes satisfy the following cell selection criteria: the cell PLMN is the selected PLMN, registered or an equivalent PLMN; the cell is not barred or reserved; and the cell is not part of a tracking area in the list of “forbidden tracking areas for roaming.”

If the UE selects a cell belonging to the same RAT and system that it was connected to prior to the failure (e.g., NR to NR, LTE/EPC to LTE/EPC, or LTE/5GC to LTE/5GC), the UE stops timer T311 (if triggered by radio link failure (RLF)) and initiates the re-establishment procedure by starting the timer T301 and transmitting the re-establishment request. However, if the UE selects an inter-RAT cell (e.g., NR to LTE/EPC or LTE/5GC, and LTE/EPC or LTE/5GC to NR), the UE will transition to RRC_IDLE and perform NAS signalling, which is less optimized than re-establishment signalling. So, if the UE is in RRC_CONNECTED in NR it will enter RRC_IDLE and upper layers may trigger a new connection. The same occurs if the UE reselects an intra-RAT/inter-system cell, e.g., the UE was connected to an LTE/EPC cell and reselects to an LTE/5GC cell, or the UE was connected to an LTE/5GC cell and reselects to an LTE/EPC cell.

The procedures to trigger the reestablishment are specified in § 5.3.7.3 of 3GPP TS 36.331 v15.3.0 (LTE) and 3GPP TS 38.331 v15.3.0 (NR). The procedures to prepare the RRCConnectionReestablishmentRequest (LTE) and the RRCReestablishmentRequest (NR) messages are specified in § 5.3.7.4 of 36.331 and 38.331, respectively. In both RRCConnectionReestablishmentRequest and RRCReestablishmentRequest messages, the UE includes a ue-Identity that enables the network to identify the UE AS Context and properly continue the re-establishment procedure by sending an RRCConnectionReestablishment or RRCReestablishment message with a Next Hop Chaining Count (NCC) for security key refresh, and an RRCConnectionReconfiguration or RRCReconfiguration message to resume signalling radio bearer 2 (SRB2) and data radio bearers (DRBs). For NR, at least, the RRCReconfiguration message can be multiplexed with the RRCReestablishment due to the fact that it is sent on integrity protected SRB1. The following discusses how the procedures and messages are defined in TS 36.331 for LTE and in TS 38.331 for NR.

In LTE, the UE initiates RRC Connection Reestablishment under any of the following conditions:

-   -   upon T310 expiry (detection of physical layer problems for the         PCell); or     -   upon T312 expiry (Measurement reporting has failed); or     -   upon random access problem indication from MCG MAC; or     -   upon indication from MCG RLC, which is allowed to be send on         PCell, that the maximum number of retransmissions has been         reached for an SRB or DRB:

FIG. 5 shows a signal flow diagram for a successful RRC Connection Reestablishment procedure in LTE. When the UE initiates the procedure, it performs cell selection and then transmits the RRCReestablishmentRequest message. However, if the UE reselects to an inter-RAT cell it will go to RRC_IDLE and perform NAS recovery.

As briefly mentioned above, details of the RRC Reestablishment procedures in LTE are specified in 3GPP TS 36.331 (v15.3.0) sections 5.3.7.3 and 5.3.7.4. Portions of these sections most relevant to the present disclosure are given below:

*** Begin 3GPP TS 36.331 excerpt ***

5.3.7.3 Actions following cell selection while T311 is running

Upon selecting an inter-RAT cell, the UE shall:

1> if the selected cell is a UTRA cell, and if the UE supports Radio Link Failure Report for Inter-RAT MRO, include selectedUTRA-CellId in the VarRLF-Report and set it to the physical cell identity and carrier frequency of the selected UTRA cell;

1> perform the actions upon leaving RRC_CONNECTED as specified in 5.3.12, with release cause ‘RRC connection failure’;

5.3.7.4 Actions related to transmission of RRCConnectionReestablishmentRequest

The UE shall set the contents of RRCConnectionReestablishmentRequest message as follows:

1> except for a NB-IoT UE for which AS security has not been activated, set the ue-Identity as follows:

-   -   2> set the c-RNTI to the C-RNTI used in the source PCell         (handover and mobility from E-UTRA failure) or used in the PCell         in which the trigger for the re-establishment occurred (other         cases);     -   2> set the physCellId to the physical cell identity of the         source PCell (handover and mobility from E-UTRA failure) or of         the PCell in which the trigger for the re-establishment occurred         (other cases);         *** End 3GPP TS 36.331 excerpt ***

FIG. 6A shows an ASN.1 data structure for an LTE RRCConnectionReestablishmentRequest message, as in 3GPP TS 36.331 (v15.3.0). Various fields of this message are defined as follows:

-   -   physCellId: Physical Cell Identity of the PCell the UE was         connected to prior to the failure.     -   reestablishmentCause: Indicates the failure cause that triggered         the re-establishment procedure. eNB is not expected to reject a         RRCConnectionReestablishmentRequest due to unknown cause value         being used by the UE.     -   ue-Identity: UE identity included to retrieve UE context and to         facilitate contention resolution by lower layers.         In addition, FIG. 6B shows an ASN.1 data structure for C-RNTI,         which identifies a UE having an RRC connection within a cell.         The field “c-RNTI” in the message shown in FIG. 6A is an         instance of the data structure shown in FIG. 6B. Likewise, FIG.         6C shows an ASN.1 data structure for PhysCellID, which is used         to indicate the physical layer identity of the cell. The field         “physCellId” in the message shown in FIG. 6A is an instance of         the data structure shown in FIG. 6C.

In NR, a UE initiates an RRC Reestablishment procedure upon any of the following:

-   -   detecting radio link failure of the MCG due to one of the         following: expiry of timer T310 in PCell, random access problem         indication from MCG MAC, or indication from MCG RLC that maximum         retransmissions has been reached.     -   re-configuration with sync failure of the MCG;     -   mobility from NR failure;     -   integrity check failure indication from lower layers for SRB1 or         SRB2; or     -   RRC connection reconfiguration failure, in accordance with         sub-clause 5.3.5.8.2.

FIG. 7A shows a signal flow diagram for a successful RRC Reestablishment procedure in NR. When the UE initiates the procedure, it performs cell selection and then transmits the RRCReestablishmentRequest message. However, if the UE reselects to an inter-RAT cell it will go to RRC_IDLE and perform NAS recovery. In addition, if the network fails to retrieve the UE context, the network can respond to the RRCReestablishmentRequest message with a RRCSetup message, which will establish a new RRC connection. FIG. 7B shows a signal flow diagram for an RRC Reestablishment procedure in NR resulting in fallback to RRC establishment, which is ultimately successful.

As briefly mentioned above, details of the RRC Reestablishment procedures in NR are specified in 3GPP TS 38.331 (v15.3.0) sections 5.3.7.3 and 5.3.7.4. Portions of these sections most relevant to the present disclosure are given below:

*** Begin 3GPP TS 38.331 excerpt ***

5.3.7.3 Actions following cell selection while T311 is running

Upon selecting an inter-RAT cell, the UE shall:

1> perform the actions upon going to RRC_IDLE as specified in 5.3.11, with release cause ‘RRC connection failure’;

5.3.7.4 Actions related to transmission of RRCReestablishmentRequest message

The UE shall set the contents of RRCReestablishmentRequest message as follows:

1> set the ue-Identity as follows:

-   -   2> set the c-RNTI to the C-RNTI used in the source PCell         (reconfiguration with sync or mobility from NR failure) or used         in the PCell in which the trigger for the re-establishment         occurred (other cases);     -   2> set the physCellId to the physical cell identity of the         source PCell (reconfiguration with sync or mobility from NR         failure) or of the PCell in which the trigger for the         re-establishment occurred (other cases);     -   2> set the shortMAC-I to the 16 least significant bits of the         MAC-I calculated:         -   3> over the ASN.1 encoded as per section 8 (i.e., a multiple             of 8 bits) VarShortMAC-Input;         -   3> with the K_(RRCint) key and integrity protection             algorithm that was used in the source PCell (reconfiguration             with sync or mobility from NR failure) or of the PCell in             which the trigger for the re-establishment occurred (other             cases); and         -   3> with all input bits for COUNT, BEARER and DIRECTION set             to binary ones;     -   2> if the re-establishment procedure was initiated due to         reconfiguration failure as specified in 5.3.5.8:         -   3> set the reestablishmentCause to the value             reconfigurationFailure;     -   2> else if the re-establishment procedure was initiated due to         reconfiguration with sync failure as specified in 5.3.5.8.3         (intra-NR handover failure) or 5.4.3.5 (inter-RAT mobility from         NR failure):     -   3> set the reestablishmentCause to the value handoverFailure;     -   2> else:         -   3> set the reestablishmentCause to the value otherFailure;

1> restore the RRC configuration and security context from the stored UE AS context;

1> restore the PDCP state and re-establish PDCP for SRB1;

1> re-establish RLC for SRB1;

1> resume SRB1;

1> The UE shall submit the RRCReestablishmentRequest message to lower layers for transmission.

*** End 3GPP TS 38.331 excerpt ***

The UE could also receive an RRCSetup message in response to an RRCRestablishmentRequest it has sent (e.g., when the gNB is not able to find the UE context). In this case, the UE performs the RRC connection establishment procedure as specified in 5.3.3.4.

FIG. 8A shows an ASN.1 data structure for an NR RRCReestablishmentRequest message, as in 3GPP TS 38.331 (v15.3.0). Various fields of this message are defined as follows:

-   -   physCellId: Physical Cell Identity of the PCell the UE was         connected to prior to the failure.     -   reestablishmentCause: Indicates the failure cause that triggered         the re-establishment procedure. The gNB is not expected to         reject a RRCReestablishmentRequest due to unknown cause value         being used by the UE.     -   ue-Identity: UE identity included to retrieve UE context and to         facilitate contention resolution by lower layers.         In addition, FIG. 8B shows an ASN.1 data structure for         RNTI-Value, which identifies a UE having an RRC connection         within a cell. The field “c-RNTI” in the message shown in FIG.         8A is an instance of the data structure shown in FIG. 8B.         Likewise, FIG. 8C shows an ASN.1 data structure for PhysCellID,         which is used to indicate the physical layer identity of the         cell. The field “physCellId” in the message shown in FIG. 8A is         an instance of the data structure shown in FIG. 8C.

Various other inter-node messages used during the RRC Reestablishment procedure in NR. These are defined in 3GPP TS 38.423 (v15.0.0) and include:

-   -   RETRIEVE UE CONTEXT REQUEST—sent by the new NG-RAN node to         request the old NG-RAN node to transfer the UE Context to the         new NG-RAN. FIG. 9A shows an exemplary structure of this         message.     -   RETRIEVE UE CONTEXT RESPONSE—sent by the old NG-RAN node to         transfer the UE context to the new NG-RAN node. FIG. 9B shows an         exemplary structure of this message.     -   NG-RAN Cell Identity—IE that contains either an NR or an E-UTRA         Cell Identity. FIG. 9C shows an exemplary structure of this IE.     -   NG-RAN node UE XnAP ID—The NG-RAN node UE XnAP ID uniquely         identifies a UE over the Xn interface within the NG-RAN node.         FIG. 9D shows an exemplary structure of this IE.     -   UE Context ID—IE used to address a UE Context within an NG-RAN         node. FIG. 9E shows an exemplary structure of this IE.

For example, if a UE is configured with NE-DC or NGEN-DC and experiences failure (e.g., radio link failure (RLF), handover failure, integrity verification failure of SRB1/2, etc.) in the MN, it performs cell selection. If the UE selects a node in the same RAT and system as the MN, the UE initiates RRC Reestablishment. However, if the UE selects an inter-RAT and/or inter-system cell, it will go to RRC_IDLE state in the target RAT. This requires the UE to trigger an RRC Connection Setup procedure in the target RAT to establish the connection from scratch, which can take a relatively longer time and consume relatively more network resources as compared to reestablishment.

FIG. 10 illustrates two scenarios in which a UE selects a PCell of a different RAT than the PCell on which the failure occurred. FIG. 10A illustrates a scenario in which the UE is in NE-DC with an NR PCell (served, e.g., by a gNB) and an LTE PScell (served, e.g., by a ng-eNB). If the UE selects an LTE PCell upon failure in the NR PCell, the UE goes to RRC_IDLE in the target LTE cell. Similarly, FIG. 10B illustrates a scenario in which the UE is in NGEN-DC with an LTE PCell (served, e.g., by a ng-eNB) and an NR PScell (served, e.g., by a gNB). If the UE selects an NR PCell upon failure in the LTE PCell, the UE goes to RRC_IDLE in the target NR cell.

Exemplary embodiments disclosed herein address these and other problems, issues, and/or drawbacks of existing DC solutions by allowing a UE operating in MR-DC (e.g., NE-DC or NGEN-DC) to perform re-establishment even towards an inter-RAT cell, thereby improving both UE and network performance as compared to going to RRC_IDLE state and establishing the connection from scratch in that inter-RAT cell. Furthermore, these exemplary embodiments address additional problems that do not exist in inter-RAT re-establishment for single-connectivity (i.e., non-DC) operation, including but not limited to handling of an AS context associated with the MN and/or SN, identification of the UE AS context, and calculation of a security token.

When a UE operating in MR-DC declares failure of its current PCell (of a first RAT) and initiates an inter-RAT RRC Reestablishment towards a selected target cell of a second RAT, the UE can include the physical cell ID (PCI) of its current PSCell and the UE's C-RNTI with respect to the current PSCell in the RRC Reestablishment Request message. Like the selected target cell, the current PSCell is of the second RAT. If the UE can reestablish in the selected target cell, the source PCI and C-RNTI can be assigned by the source MN serving the current PCell of the first RAT, rather than by the source SN serving the current PSCell of the second RAT.

Accordingly, one particular advantage provided by the exemplary embodiments is that a UE in inter-RAT MR-DC (e.g., NE-DC or NGEN-DC) can reuse parameters associated with its SN/PSCell/SCG to reestablish a connection with a target PCell (of the same RAT as the SN) after a failure in its current PCell (of a different RAT than the target PCell). This not only reduces interruption time but also can enable inter-RAT reestablishment without the need to modify the RRC messages used to transmit parameters from different RATs with different formats.

In some embodiments, when a UE operating in RRC_CONNECTED mode in MR-DC (e.g., connections with MN and SN of different RATs) declares a failure (e.g., in the MN PCell) and selects a target cell of a different RAT than the current PCell, it initiates an inter-RAT RRC Reestablishment procedure if one or more criteria are met. Otherwise, if the one or more criteria are not met, the UE goes to RRC_IDLE, where it can perform a more time-consuming RRC Connection Setup procedure.

For example, upon failure of the MN, the connection quality in the PSCell served by the UE can still be good, causing the UE to select an inter-RAT cell from the same RAT as the SN (e.g., another cell provided by the SN in the same RAT). Instead of deleting the SN context, exemplary embodiments enable the UE to maintain the SN context and perform re-establishment.

FIG. 11 illustrates the same two scenarios shown in FIG. 10 , but with improvements according to various exemplary embodiments of the present disclosure. FIG. 11A illustrates the situation where the UE is in NE-DC with an NR PCell (served, e.g., by a gNB) and an LTE PScell (served, e.g., by a ng-eNB). If the UE selects an LTE PCell upon failure in the NR PCell, the UE performs re-establishment in the target LTE cell. Similarly, FIG. 11B illustrates this situation where the UE is in NGEN-DC with an LTE PCell (served, e.g., by a ng-eNB) and an NR PScell (served, e.g., by a gNB). If the UE selects an NR PCell upon failure in the LTE PCell, the UE performs re-establishment in the target NR cell.

Upon initiating the inter-RAT RRC Reestablishment procedure, the UE can perform various operations including handling (e.g., storing) the AS context associated with the MN and the SN, computing a security token (e.g., MAC-I), and setting the AS context identifier according to various rules and criteria discussed in more detail below. In addition, the UE can include identifiers of the physical cell ID (PCI) and the C-RNTI associated with the source cell in the reestablishment request message (e.g., RRCConnectionReesestablishmentRequest or RRCReestablishmentRequest). Note that the included source PCI and C-RNTI have been assigned by a different RAT than the RAT of the target cell in which the UE is reestablishing the connection. Upon receiving one or more responsive messages (e.g., re-establishment and/or reconfiguration messages) from a network node serving the target cell, the UE can complete the connection re-establishment with the target cell.

In some embodiments, when a UE operating in MR-DC reselects to an inter-RAT cell in the same RAT as the last serving SN, the UE calculates a short MAC-I to be included in the reestablishment request message (e.g., RRCConnectionReesestablishmentRequest or RRCReestablishment-Request) using the security parameters associated with the SCG, the PCI of the PSCell, the C-RNTI that was allocated by the SN, and the target cell ID. Since the PCI and C-RNTI are in a different format than the target Cell ID, various procedures can be applied. Even so, the UE can include PCI and C-RNTI allocated by the SN and the target cell ID in the reestablishment request message, rather than PCI and C-RNTI allocated by the source MN.

In some embodiments, a network can comprise a first network node providing connectivity to a UE, via a first RAT, as the master node (source MN) of a PCell, and a second network node providing connectivity, via a different second RAT, to the same UE as the secondary node (source SN) of a PSCell. The network can also include a target node that, after the UE selects a target cell served by the target node for re-establishment of a connection, receives the reestablishment request message (e.g., RRCConnectionReesestablishmentRequest or RRCReestablishment-Request) containing the parameters discussed above in relation to the UE embodiments. The target node can use the included PCI to locate the UE's source SN (e.g., via automatic neighbor relations) that has the stored UE SN context. The target node then sends a RETRIEVE UE CONTEXT REQUEST to this source SN, including that C-RNTI that was included in the UE's message. In some embodiments, the target node may be the same as the source SN.

Upon receiving this request, the source SN can retrieve the stored UE SN context based on the C-RNTI included in the message, and from it can determine a reference to the source MN and the UE identity used by the MN (e.g., an XnAP Identity). Using the information in this stored UE context (e.g., security keys/algorithms, source SN C-RNTI, PSCell PCI) as well as the target cell ID that was sent by the UE, the SN can calculate an XMAC-I and compare it with short MAC-I sent by the UE. If there is a match, the source SN sends a context request to the source MN, including in it the UE identity used by the source MN that was determined based on the stored UE SN context.

Furthermore, upon receiving this request, the source MN uses this identity (e.g., an XnAP identity) to locate the UE context that it has stored. The source MN than responds to the target node with the full UE context. After receiving this information, the target node sends an RRCReestablishment message to the UE.

In some embodiments where the UE attempts re-establishment while operating in NE-DC (i.e., NR source MN, E-UTRA source SN, E-UTRA target node), the target cell ID is the E-UTRA Cell ID as defined in 3GPP TS 36.331 (v15.3.0) section 9.2.2.9. In other embodiments where the UE attempts re-establishment while operating in NGEN-DC (i.e., E-UTRA source MN, NR source SN, NR target node), the target cell ID is the NR Cell ID as defined in 3GPP TS 38.331 section 9.2.2.9. Although both of these embodiments involve MR-DC with both RATs connected to a 5GC, similar procedures can be applied in other embodiments where both RATs are connected to an EPC or, more generally, in any other inter-RAT DC scenario.

In general, the described embodiments include a UE reestablishing in only a single connectivity. Nevertheless, other embodiments include the situation where the UE establishes a secondary connection (e.g., with a SN) in the RRC Reestablishment procedure. In such case, the disclosed procedures would still apply but with an additional configuration of the SN during such reestablishment.

As mentioned above, a UE connected in MR-DC with the MN in a first RAT and the SN in a second RAT (e.g., NGEN-DC or NE-DC) can trigger a re-establishment procedure when the UE experiences a failure in the MCG associated with the MN. For instance, such failures can include a radio link failure, a failure during handover, integrity verification check failure on SRB1/2, etc. Upon detecting the failure, the UE performs configured measurements on various cells, and then reselects the target cell based on the configured measurements. This target cell can be any measured cell, including the same cell in which the UE experienced the failure.

According to various embodiments, the UE can trigger an inter-RAT re-establishment procedure if the selected target cell meets at least one predetermined condition. For example, the UE can trigger the re-establishment procedure based on one or more of the following conditions:

-   -   Target cell is from the same RAT as the SN (possibly including         further restrictions such as the target cell is the UE's SpCell         in the SN or any other SCell associated to the SN);     -   Target cell is from the same RAT as the MN (in this case, the UE         can trigger a conventional intra-RAT re-establishment         procedure);     -   Target cell is from the same Core Network (CN) type as the MN         (e.g. 5GC, EPC, etc.); and/or     -   Target cell is from the same CN type as the SN.

For example, such conditions can be specified for NR according to the following text, which can be included in a 3GPP specification such as 3GPP TS 38.331:

*** Begin exemplary text for 3GPP specification ***

5.3.7.3 Actions following cell selection while T311 is running

Upon selecting a suitable NR cell, the UE shall:

1> stop timer T311;

1> start timer T301;

1> apply the timeAlignmentTimerCommon included in SIB1;

1> initiate transmission of the RRCReestablishmentRequest message in accordance with 5.3.7.4;

NOTE: This procedure applies also if the UE returns to the source PCell.

Upon selecting an inter-RAT cell, the UE shall:

1> if the UE is in NR-DC, MR-DC, multi-radio connectivity with the SN in a second RAT;

-   -   2> if the selected cell is in the same RAT as the cell of the SN         (SpCell); or     -   2> if the selected cell is in the same RAT as the cell of the         MN; or     -   2> if the selected cell is in the CN type as the cell of the SN;         or     -   2> if the selected cell is in the CN type as the cell of the MN;         -   3> initiate transmission of the RRCReestablishmentRequest             message in accordance with 5.3.7.4.2 in 36.331;     -   2> else:         -   3> perform the actions upon going to RRC_IDLE as specified             in 5.3.11, with release cause ‘RRC connection failure’.             *** End exemplary text for 3GPP specification ***

Upon initiating the re-establishment procedure, the UE can store the AS contexts associated with the MN and the SN according to various embodiments. For example, the UE can store the AS context associated with the MN in case the inter-RAT reestablishment supports delta signaling for the MN configuration (e.g. in the first reconfiguration message after the Reestablishment message). For example, the UE can store the AS context associated with the SN in case the inter-RAT reestablishment supports delta signaling for the SN configuration (e.g. in the first reconfiguration message after the Reestablishment message). In case the SN- and MN-related RRC configurations are signaled independently, each of these AS context storage can be performed independent of the other. For example, such operations can be specified for NR according to the following text, which can be included in a 3GPP specification such as 3GPP TS 38.331.

*** Begin exemplary text for 3GPP specification ***

5.3.7.2 Initiation

The UE initiates the procedure when one of the following conditions is met:

1> upon detecting radio link failure of the MCG, in accordance with 5.3.10; or

1> upon re-configuration with sync failure of the MCG, in accordance with sub-clause 5.3.5.8.3; or

1> upon mobility from NR failure, in accordance with sub-clause 5.4.3.5; or

1> upon integrity check failure indication from lower layers concerning SRB1 or SRB2; or

1> upon an RRC connection reconfiguration failure, in accordance with sub-clause 5.3.5.8.2.

Upon initiation of the procedure, the UE shall:

1> stop timer T310, if running;

1> stop timer T304, if running;

1> start timer T311;

-   -   1> suspend all RBs, except SRB0;     -   1> reset MAC;     -   1> release the MCG SCell(s), if configured, in accordance with         sub-clause 5.3.5.5.8;     -   1> release the current dedicated ServingCell configuration and         apply the specified values in corresponding specification except         for the parameters for which values are provided in SIB1;     -   1> store the UE AS Context including the current RRC         configuration associated to the SN (at least the SpCell), the         current security context, the PDCP state including ROHC state,         SDAP configuration, C-RNTI used in the source PCell, the         cellIdentity and the physical cell identity of the source PCell;     -   1> store the UE AS Context including the current RRC         configuration associated to the MN (at leas the SpCell), the         current security context, the PDCP state including ROHC state,         SDAP configuration, C-RNTI used in the source PCell, the         cellIdentity and the physical cell identity of the source PCell;     -   1> release delayBudgetReportingConfig, if configured, and stop         timer T3xx, if running;     -   1> apply the default MAC Cell Group configuration as specified         in 9.2.x1;     -   1> perform cell selection in accordance with the cell selection         process as specified in TS 38.304 [21].         *** End exemplary text for 3GPP specification ***

The identity that the UE uses when requesting an RRC reestablishment consists of the UE's source cell C-RNTI and the source cell PCI. As shown in FIGS. 6B-C (LTE) and 8B-C (NR), each of these parameters is expressed in different formats between LTE and NR, such that parameters for one RAT are not recognizable by the other RAT. Even so, since the UE is known by the second RAT in the SN where the UE has been assigned a C-RNTI for the PSCell and has obtained the PCI of the PSCell, UE can use these PSCell parameters during inter-RAT reestablishment in NE-DC or NGEN-DC according to various embodiments described in more detail below.

As mentioned above, in some embodiments, the verification of the UE identity can be performed by the source MN. Since the source MN belongs to a different RAT than the target RAT (i.e., source MN is NR while target node is E-UTRA), the source PCI and C-RNTI will be in a different format than the target cell parameters. In order to calculate the shortMAC-I, either the source parameters or target parameters need to be adapted to the format of the other in order to use existing procedures to calculate the short MAC-I. Alternately, other procedures can be introduced to utilize parameters of different RATs directly in the calculations of the short MAC-I. Exemplary embodiments of such other procedures are disclosed in U.S. Prov. Appl. 62/735,872, which is incorporated herein by reference in its entirety.

In some embodiments, during NE-DC operation when the UE detects a failure associated with the source MgNB PCell, the UE can select a target cell associated with the source SN (e.g., SeNB). For example, the selected target cell can be the PSCell, another SCell belonging to the SCG, or a cell that belongs to the SN but was not associated with the UE before the failure was detected. In such case, the UE prepares a RRCConnectionReestablishmentRequest message using the PSCell C-RNTI and PSCell PCI to identify the UE, and sends it to the source SN. Also included in the message is a short MAC-I that was to calculated by the UE based on the source PSCell C-RNTI, the source PSCell PCI, and the target cell ID. Since both the source SN and the target node are LTE E-UTRA nodes in NE-DC, the procedures to calculate the shortMAC-I as well as the integrity protection algorithms used are defined in 3GPP E-UTRA specifications.

FIG. 12 shows an exemplary signaling diagram for an inter-RAT reestablishment during NE-DC operation, according to certain exemplary embodiments. This scenario involves a UE 1210, a current serving MgNB 1220 (providing the UE's current PCell), and a current serving SeNB 1240 (providing the UE's current PSCell), which is also the target node providing a target cell selected by the UE as a replacement for the current PCell, as explained in more detail below. Although the operations shown in FIG. 12 are given numerical labels, these labels are for the purpose of explanation and do not limit the operations to occur in a particular order.

In operation 0, the UE is in NE-DC. Since it is in RRC_CONNECTED state, it has received the C-RNTI from the both the MgNB and SeNB, and is also aware of the PCIs of the PCell (MgNB) and PSCell (SeNB). In operation 1, the UE detects failure whereupon it reselects to a cell belonging to the source eNB and triggers re-establishment. In operation 2, the UE obtains the E-UTRA Cell identity from the target cell (e.g., from SIB1).

In operation 3, the UE calculates the security token (e.g., short MAC-I) based on the PCI and C-RNTI of the source PSCell (in the SN) and the target Cell ID, rather than based on the PCI and C-RNTI of the source PCell (in the MN) as in conventional operation. This is done because the source PSCell PCI and C-RNTI and the target Cell ID are in E-UTRA format—which facilitates the calculation of short MAC-I—while the source PCell C-RNTI and PCI are in the different NR format discussed above. Since the calculation uses the format of the source SN, the security key and integrity protection algorithm will also be associated with the SN (e.g., the S-KeNB).

In operation 4, the UE sends a RRCConnectionReestablishmentRequest message to the target cell eNB. Since the UE is aware that the target cell is of a different RAT than the source MN, the UE includes UE identity and PCI associated with the source PSCell together with the calculated shortMAC-I and a reestablishment cause. In this case, since the source PScell is LTE E-UTRA, the included UE identity is the 16-bit C-RNTI and the included PCI is the nine-bit PCI of the SeNB.

In operation 5, when the target eNB (i.e., source SN/SeNB) receives the RRCConnectionReestablishmentRequest message, the target eNB locates the UE SN Context using the source PSCell C-RNTI and source PSCell PCI included in the message. The UE SN context contains the SeNB security context (with S-KeNB and security algorithms) as well as the M-NG-RAN node UE XnAP ID that was used to identify the UE in communication between the source MN and source SN over the Xn interface.

In operation 6, the target eNB calculates the XMAC-I using the source PSCell C-RNTI and PCI values and the target Cell ID included in the message, as well as the security key (S-KeNB) and security algorithms associated with the SN. The source SeNB then verifies the UE identity by comparing the calculated XMAC-I and the received short MAC-I. If there is a match, the procedure continues. Otherwise, the re-establishment procedure is aborted

In operation 7, the target eNB sends a RETRIEVE MN UE CONTEXT REQUEST message to the source MN. This message contains the M-NG-RAN node UE XnAP ID that was used by the source MN to identify the UE, the NG-RAN node UE XnAP ID that is used by the source SN to identify the UE, the short MAC-I sent by the UE, and the target cell PCI. As compared to a conventional RETRIEVE UE CONTEXT REQUEST message, the RETRIEVE MN UE CONTEXT REQUEST message additionally includes the M-NG-RAN node UE XnAP ID and does not include the source MgNB C-RNTI and source MgNB PCI (e.g., which identifies the UE context) nor the short MAC-I.

In operation 8, after receiving the RETRIEVE MN UE CONTEXT REQUEST message, the source MN (i.e., last serving MgNB) locates the UE context based on source MN's UE XnAP ID that was included in the message sent in operation 6. Since 3GPP TS 38.423 (v15.0.0) requires that “The NG-RAN node UE XnAP ID shall be unique within the logical NG-RAN node”, the source MN is able to uniquely identity the UE based on UE XnAP ID provided in the context request. Unlike existing and/or legacy procedures, the source MN will not perform integrity verification but instead responds in operation 9 by sending the UE context. For example, this message sent in operation 9 can be an existing RETRIEVE UE CONTEXT RESPONSE message.

Note that in some cases, after operation 9, the source SN may need to consider the latest SCG configurations (e.g., if SRB3 was configured) and the source MN may not have the latest configurations. The configurations can be added to the configurations sent by the source MN in operation 9.

In operation 10, the target eNB transmits a RRCConnectionReestablishment message to the UE. This is used to set up SRB1. In operation 11, The UE transmits RRCConnectionReestablishmentComplete message to the target eNB. In operation 12, the target eNB sends an RRCConnectionReconfiguration message to setup SRB2 and DRBs. In operation 13, the UE responds to the target eNB with a RRCConnectionReconfigurationComplete message.

With respect to operations 10-13, currently the existing LTE RRCConnectionReestablishment message is sent over SRB0. In NR, the existing RRCReestablishment message is sent via SRB1. Similar enhancements can be envisioned where SRB1 can be used for sending the LTE RRCConnectionReestablishment message. In that case, the RRCConnectionReconfiguration can be multiplexed with the RRCConnectionReestablishment message, such that the target eNB doesn't have to wait for the RRCConnectionReestablishmentComplete message before sending the RRCConnectionReconfiguration message. In some embodiments, the LTE RRCConnectionReestablishment message can be modified to include IEs needed for reconfiguring SRB2 and DRBs. In contrast, legacy reestablishment is used to reconfigure only SRB1 and an additional RRCConnectionReconfiguration message is required to setup SRB2 and DRBs.

In operation 14, the last serving gNB provides forwarding addresses to prevent loss of DL user data buffered in the this gNB. In operations 15-16, the CN path is switched to the target eNB. In operation 17, the target eNB triggers the release of the UE resources at the last serving MgNB. In addition, the target eNB could release the resources associated with the UE, such as resources that were used at the target eNB for holding the information associated with the UE while connected in DC before the re-establishment request was received. In operation 18, the UE resumes operation in RRC_CONNECTED mode.

FIG. 13 shows an exemplary signaling diagram for another inter-RAT reestablishment during NE-DC operation, according to certain exemplary embodiments. This scenario involves a UE 1310, a current serving MgNB 1320 (providing the UE's current PCell), a current serving SeNB 1330 (providing the UE's current PSCell), and a target eNB 1340 (different from SeNB 1330) providing a target cell selected by the UE as a replacement for the UE's current PCell. Although the operations shown in FIG. 13 are given numerical labels, these labels are for facilitating explanation and do not limit the operations to occur in a particular order. The following description omits operations that are substantially identical to operations shown in FIG. 12 . In other words, the descriptions of operations in FIG. 12 apply to the operations in FIG. 13 unless otherwise noted below, taking into account any difference in number labelling for substantially identical operations.

In operations 4-5, when the target eNB receives the RRCConnectionReestablishmentRequest message, it determines that the requested UE was not being served by it since the included PCI doesn't belong to one of the cells that the target eNB serves. In response, the target eNB can send a legacy RETRIEVE UE CONTEXT REQUEST message to the source eNB, which the target eNB identified based on the PCI included in RRCConnectionReestablishment-Request message.

Operations 6-8 of FIG. 13 are similar to operations 5-7 of FIG. 12 . However, in the procedure shown in FIG. 13 , the target eNB sending the RETRIEVE UE CONTEXT REQUEST message is different from the last serving eNB, as indicated in the target Cell ID. Accordingly, in operation 10, the source MN (e.g., last serving MgNB) sends the RETRIEVE UE CONTEXT RESPONSE message to a node different from the node that sent the RETRIEVE UE CONTEXT REQUEST message. Since the Cell ID in the RETRIEVE UE CONTEXT REQUEST message contains the eNB ID (as defined in 3GPP TS 38.423 v15.0.0 section 9.2.2.9), the source MN can determine the destination for the response message.

Alternately, in operation 10, the source MN can send the UE CONTEXT RETRIEVE RESPONSE message to the source SN, and the source SN can send a UE CONTEXT RETRIEVE RESPONSE message to the target node (e.g., in an operation 10 a, not shown). The source SN can include the latest SCG configurations with the received UE context in this message sent to the target node. In operation 15, data forwarding address could also be indicated towards the source SeNB, e.g., for forwarding data of SN terminated bearers.

Otherwise, operations 8-18 of FIG. 13 are similar to operations 7-17 of FIG. 12 . In operation 18 of FIG. 13 , the target eNB sends a UE CONTEXT RELEASE message to the source MN. In operation 19, however, the source MN also sends a UE CONTEXT RELEASE message to the source SN (e.g., last serving SeNB).

Exemplary embodiments related to inter-RAT reestablishment during UE operation in NGEN-DC are substantially similar to those for inter-RAT reestablishment during NE-DC operation, discussed above with respect to FIGS. 12-13 . However, the reversal of the DC roles of the two RATs introduces a requisite change in the various terminology used to describe these embodiments. For example, “source MgNB” becomes “source MeNB,” with corresponding changes to all associated parameters (e.g. PCI_source_MgNB will change to PCI_source_MeNB, etc.). In addition, “source SeNB” becomes “source SgNB,” with corresponding changes to all associated parameters. Likewise, “target eNB” becomes “target gNB” with corresponding changes to all associated parameters, and the messages sent to/from the UE will be NR RRC messages instead of E-UTRA RRC messages. Furthermore, any NR- or E-UTRA-specific procedure within the operations of FIGS. 10-11 will be a corresponding procedure specific to the opposite RAT during NGEN-DC operation.

FIG. 14 shows an exemplary signaling diagram for another inter-RAT reestablishment during NGEN-DC operation, according to certain exemplary embodiments. This scenario involves a UE 1410, a current serving MeNB 1420 (providing the UE's current PCell), a current serving SgNB 1430 (providing the UE's current PSCell), and a target gNB 1440 (different from SgNB 1430) providing a target cell selected by the UE as a replacement for the UE's current PCell. Although the operations shown in FIG. 14 are given numerical labels, these labels are for facilitating explanation and do not limit the operations to occur in a particular order. The descriptions of operations in FIGS. 12 and/or 13 apply to the operations in FIG. 14 , taking into account any difference in number labelling for substantially identical operations, as well as the terminology differences between NE-DC and NGEN-DC, as discussed above.

Note that the NR RRCReestablishment message is sent via SRB1, so it can be multiplexed together with the RRCReconfiguration message, similar to embodiments discussed above with respect to NE-DC operation. In some embodiments, the NR RRCReestablishment message can be modified to include IEs needed for reconfiguring SRB2 and DRBs, similar to embodiments discussed above with respect to NE-DC operation.

As mentioned above, in some embodiments, when the Source SN sends the RETRIEVE UE CONTEXT REQUEST message to the source MN, it can include the latest SCG configurations and the source MN can compile a complete UE configuration based on that. This can be useful when SRB3 was configured in the source SN, and some SCG reconfigurations were performed by the source SN without involving the source MN.

As also mentioned above, in some embodiments, when the source MN has verified the UE identity and prepares to send the RETRIEVE UE CONTEXT RESPONSE message, instead of sending the message directly to the target node, it responds to the source SN using the XnAP_ID_source_eNB instead of XnAP_ID_target_eNB for NE-DC (or equivalent for source gNB and target gNB in NGEN-DC). The source SN can then forward the UE Context in a RETRIEVE UE CONTEXT RESPONSE message to the target node (eNB or gNB).

In some embodiments, the network can indicate whether the UEs and network nodes involved in reestablishment should perform procedures in the manner outlined above, or instead should perform the procedures in an existing and/or legacy manner. This can be indicated via dedicated signaling (e.g., RRCReconfiguration or RRCConnectionReconfiguration message), or using broadcast signaling (e.g., SIBs).

In various embodiments discussed above, there was identified a need for a new message, or modification to an existing message, to forward a RETRIEVE UE CONTEXT REQUEST message from the SN to the MN. For example, such message can be referred to as RETRIEVE MN UE CONTEXT REQUEST. As compared to existing messages, the difference is that the UE Context (including C-RNTI and the source MN failure cell PCI) is not included, while a new field called ‘Old M-NG-RAN node UE XnAP ID Reference’ is included. In other embodiments, the existing RETRIEVE UE CONTEXT REQUEST message can be extended to optionally include a new field ‘Old M-NG-RAN node UE XnAP ID Reference.’ This message can also be modified to not include the UE Context ID if this new field is included, or the target node receiving the message can simply ignore a UE Context ID field if the new field is also included.

FIG. 15 shows an exemplary RETRIEVE MN UE CONTEXT REQUEST message according to various embodiments of the present disclosure. The exemplary message shown in FIG. 15 can be sent from a current serving SN to a current serving MN. The message is similar in structure to the RETRIEVE UE CONTEXT REQUEST message shown in FIG. 9A, except that it includes the field Old M-NG-RAN node UE XnAP ID reference, which provides a UE identifier recognizable by the recipient MN. For example, the exemplary message shown in FIG. 15 can be included in a 3GPP specification, such as 3GPP TS 38.423 (v15.0.0).

Embodiments discussed above in relation to FIGS. 11-15 are further illustrated by FIGS. 16-18 , which show flow diagrams of exemplary methods and/or procedures performed by network nodes or UEs. For example, aspects of the various embodiments discussed in relation to FIGS. 11-15 are features of the operations shown in FIGS. 16-18 .

More specifically, FIG. 16 is a flow diagram illustrating an exemplary method and/or procedure for establishing a connection with a UE operating in dual connectivity (DC) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN), and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN), according to various exemplary embodiments of the present disclosure. The exemplary method and/or procedure shown in FIG. 16 can be implemented by a target node (e.g., eNB, gNB, ng-eNB, or components thereof) with respect to the UE. Furthermore, the exemplary method and/or procedure shown in FIG. 16 can be utilized cooperatively with other exemplary methods and/or procedures described herein (e.g., FIGS. 17-18 ) to provide various exemplary benefits described herein. Although FIG. 16 shows blocks in a particular order, this order is merely exemplary and the operations of the exemplary method and/or procedure can be performed in a different order than shown, and can be combined and/or divided into blocks having different functionality than shown. Optional operations are indicated by dashed lines.

The exemplary method and/or procedure illustrated in FIG. 16 can include the operations of block 1610, in which the target node can receive, from the UE, a re-establishment request message comprising a plurality of parameters associated with the PSCell, a first message authentication code (MAC), and an indication of the UE's selection of a target cell served by the network node as a replacement for the PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell and the target cell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA).

In some embodiments, the MAC included in the re-establishment request message is based on a plurality of parameters associated with the PSCell and on an identifier of the target cell. In some embodiments, the plurality of parameters associated with the PSCell can include an identifier of the PSCell, an identifier of the UE in relation to the PSCell, and integrity protection information associated with the SN.

The exemplary method and/or procedure can also include the operations of block 1620, in which the target node can verify the integrity of the re-establishment request message based on the first MAC. The exemplary method and/or procedure can also include the operations of block 1630, in which the target node can determine a full UE context for the UE based on the plurality of parameters associated with the PSCell, and on a successful verification of the integrity of the re-establishment request message (e.g., in block 1620).

In some embodiments, the operations of block 1630 can include the operations of sub-blocks 1631, 1632, and 1635. In sub-block 1631, the target node can perform the following operations based on the plurality of parameters associated with the PSCell: determining that the target node is the same as the SN, and retrieving a UE context associated with the SN, wherein the UE context associated with the SN includes a first identifier of the UE in relation to the MN. In sub-block 1632, the target node can send, to the MN, a context request message including the first identifier of the UE in relation to the MN. In sub-block 1635, the target node can receive, from the MN, a context response message including the full UE context.

In some embodiments, the UE context associated with the SN includes integrity protection information associated with the SN. In such embodiments, the integrity verification operations of block 1620 can include the operations of sub-blocks 1621 and 1622. In sub-block 1621, the target node can calculate a second MAC based on an identity of the target cell, the plurality of parameters associated with the PSCell, and the integrity protection information associated with the SN. In some embodiments, the identifier of the target cell can be included in the re-establishment request message.

In sub-block 1622, the target node can compare the first MAC and the second MAC to determine if there is a match between the first MAC and the second MAC, wherein a match indicates successful verification of the integrity. In some embodiments, the context request message can be sent to the MN (e.g., in sub-block 1632) based on determining that there is a match between the first MAC and the second MAC.

In other embodiments, the operations of block 1630 can include the operations of sub-blocks 1633, 1634, and 1635. In sub-block 1633, the target node can, based on the plurality of parameters associated with the PSCell, determine that the target node is different than the SN. In sub-block 1634, the target node can send, to the SN, a context request message including the plurality of parameters associated with the PSCell. In such embodiments, the integrity verification operations of block 1620 can include the operations of sub-block 1623, where the target node can send the first MAC for verification by the SN, e.g., included in the context request message sent in sub-block 1634. In sub-block 1635, the target node can receive, from the MN, a context response message including the full UE context (e.g., based on a successful verification of the first MAC by the SN).

In addition, FIG. 17 is a flow diagram illustrating an exemplary method and/or procedure performed by a user equipment (UE) operating in dual connectivity (DC) in a radio access network (RAN) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN) and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN), according to various exemplary embodiments of the present disclosure. The exemplary method and/or procedure shown in FIG. 17 can be utilized cooperatively with other exemplary methods and/or procedures described herein (e.g., FIGS. 16 and/or 18 ) to provide various exemplary benefits described herein. Although FIG. 17 shows blocks in a particular order, this order is merely exemplary and the operations of the exemplary method and/or procedure can be performed in a different order than shown, and can be combined and/or divided into blocks having different functionality than shown. Optional operations are indicated by dashed lines.

The exemplary method and/or procedure illustrated in FIG. 17 can include the operation of block 1710, in which the UE can detect a failure associated with the PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA). The exemplary method and/or procedure can also include the operation of block 1720, in which the UE can select a target cell served by a target node as a replacement for the PCell. For example, the target cell can utilize the second RAT, i.e., the same RAT as the UE's current PSCell.

In some embodiments, the exemplary method and/or procedure can also include the operations of block 1730, in which the UE can, based on determining that the target cell does not meet at least one of a set of conditions, transition to idle mode and sending a connection setup request message to the target node. The set of conditions can include the target cell being from: the same RAT as the SN, the same RAT as the MN, the same Core Network (CN) type as the MN, or the same CN type as the SN.

The exemplary method and/or procedure can also include the operations of block 1740, in which the target node can calculate a message authentication code (MAC) for a re-establishment request message based on a plurality of parameters associated with the PSCell. In some embodiments, the plurality of parameters associated with the PSCell can include an identifier of the PSCell, and an identifier of the UE in relation to the PSCell. In some embodiments, the calculation of the MAC can be further based on an identifier of the target cell.

The exemplary method and/or procedure can also include the operations of block 1750, in which the target node can send, to the target node, a re-establishment request message comprising the plurality of parameters associated with the PSCell, the calculated MAC, and an indication of the UE's selection of the target cell as a replacement for the PCell. In some embodiments, the exemplary method and/or procedure can also include the operations of block 1760, in which the target node can establish a connection with the target node, whereby the target cell served by the target node will serve as a PCell for DC.

In some embodiments, the operations of block 1760 can include the operations of sub-block 1761, where the target node can receive a connection re-establishment message from the target node over a first signaling radio bearer (SRB) via the target cell. In some embodiments, the connection reconfiguration message can include fields usable to configure at least one of the following between the target node and the UE: one or more additional SRBs, and one or more data radio bearers (DRBs).

In other embodiments, the operations of block 1760 can also include the operations of sub-block 1762, where the target node can receive a connection reconfiguration message from the target node over the first SRB via the target cell. For example, the connection reconfiguration message can be received without the UE sending a response to the connection re-establishment message.

In addition, FIG. 18 is a flow diagram illustrating an exemplary method and/or procedure performed by a secondary node (SN), in a radio access network (RAN), that is operating in dual connectivity (DC) toward a user equipment (UE) together with a master node (MN) serving the UE's current primary cell (PCell) that is part of a master cell group (MCG), according to various exemplary embodiments of the present disclosure. The exemplary method and/or procedure shown in FIG. 18 can be implemented by a network node (e.g., eNB, gNB, ng-eNB, or components thereof) serving the UE's current primary secondary cell (PSCell) that is part of a secondary cell group (SCG). Furthermore, the exemplary method and/or procedure shown in FIG. 18 can be utilized cooperatively with other exemplary methods and/or procedures described herein (e.g., FIGS. 16-17 ) to provide various exemplary benefits described herein. Although FIG. 18 shows blocks in a particular order, this order is merely exemplary and the operations of the exemplary method and/or procedure can be performed in a different order than shown, and can be combined and/or divided into blocks having different functionality than shown. Optional operations are indicated by dashed lines.

The exemplary method and/or procedure shown in FIG. 18 can include the operations of block 1810, where the SN can receive, from a target node in the RAN, a context request message pertaining to the UE. The context request message can include a plurality of parameters associated with the UE's current PSCell, a first message authentication code (MAC), and an identifier of a target cell, served by the target node, that was selected by the UE as replacement for the UE's current PCell. For example, the PCell can utilize a first radio access technology (RAT), while the PSCell and the target cell can utilize a second RAT different from the first RAT. In some embodiments, one of the first RAT and the second RAT is New Radio (NR), while the other of the first RAT and the second RAT is Long-Term Evolution Evolved UTRA (LTE E-UTRA).

The exemplary method and/or procedure can also include the operations of block 1820, where the SN can, based on the plurality of parameters associated with the UE's current PSCell, provide the target node with a full UE context for the UE.

In some embodiments, the operations of block 1820 can include the operations of sub-blocks 1821 and 1824. In sub-block 1821, the target node can retrieve a UE context associated with the SN based on the plurality of parameters associated with the UE's current PSCell. In some embodiments, the UE context associated with the SN can include an identity of the UE in relation to the MN. In sub-block 1824, the target node can send, to the MN, a request to provide the full UE context to the target node, wherein the request for the full UE context includes the identifier of the target cell served by the target node (e.g., received in block 1810). In some embodiments, the request to provide the full UE context can also include the identity of the UE in relation to the MN.

In some embodiments, the operations of block 1820 can also include the operations of sub-blocks 1822 and 1823. In sub-block 1822, the target node can calculate a second MAC based on the plurality of parameters associated with the UE's current PSCell. In some embodiments, the plurality of parameters associated with the UE's current PSCell can include an identifier of the PSCell, and an identifier of the UE in relation to the PSCell. In some embodiments, calculating the second MAC can be further based on the identifier of the target cell (e.g., received in block 1810). In sub-block 1823, the target node can compare the second MAC to the first MAC to determine if there is a match between the first MAC and the second MAC. Based on determining that there is a match between the first MAC and the second MAC, the target node can send the request to provide the full UE context (e.g., in sub-block 1824).

Although the subject matter described herein can be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a wireless network, such as the example wireless network illustrated in FIG. 19 . For simplicity, the wireless network of FIG. 19 only depicts network 1906, network nodes 1960 and 1960 b, and WDs 1910, 1910 b, and 1910 c. In practice, a wireless network can further include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or end device. Of the illustrated components, network node 1960 and wireless device (WD) 1910 are depicted with additional detail. The wireless network can provide communication and other types of services to one or more wireless devices to facilitate the wireless devices' access to and/or use of the services provided by, or via, the wireless network.

The wireless network can comprise and/or interface with any type of communication, telecommunication, data, cellular, and/or radio network or other similar type of system. In some embodiments, the wireless network can be configured to operate according to specific standards or other types of predefined rules or procedures. Thus, particular embodiments of the wireless network can implement communication standards, such as Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, or 5G standards; wireless local area network (WLAN) standards, such as the IEEE 802.11 standards; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave and/or ZigBee standards.

Network 1906 can comprise one or more backhaul networks, core networks, IP networks, public switched telephone networks (PSTNs), packet data networks, optical networks, wide-area networks (WANs), local area networks (LANs), wireless local area networks (WLANs), wired networks, wireless networks, metropolitan area networks, and other networks to enable communication between devices.

Network node 1960 and WD 1910 comprise various components described in more detail below. These components work together in order to provide network node and/or wireless device functionality, such as providing wireless connections in a wireless network. In different embodiments, the wireless network can comprise any number of wired or wireless networks, network nodes, base stations, controllers, wireless devices, relay stations, and/or any other components or systems that can facilitate or participate in the communication of data and/or signals whether via wired or wireless connections.

Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points) and base stations (BS, e.g., radio base stations, NBs, eNBs, and gNBs). Base stations can be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and can then also be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station can be a relay node or a relay donor node controlling a relay. A network node can also include one or more (or all) parts of a distributed radio base station such as centralized digital units and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station can also be referred to as nodes in a distributed antenna system (DAS).

Further examples of network nodes include multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), core network nodes (e.g., MSCs, MMEs), O&M nodes, OSS nodes, SON nodes, positioning nodes (e.g., E-SMLCs), and/or MDTs. As another example, a network node can be a virtual network node as described in more detail below.

In FIG. 19 , network node 1960 includes processing circuitry 1970, device readable medium 1980, interface 1990, auxiliary equipment 1984, power source 1986, power circuitry 1987, and antenna 1962. Although network node 1960 illustrated in the example wireless network of FIG. 19 can represent a device that includes the illustrated combination of hardware components, other embodiments can comprise network nodes with different combinations of components. It is to be understood that a network node comprises any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods and/or procedures disclosed herein. Moreover, while the components of network node 1960 are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, a network node can comprise multiple different physical components that make up a single illustrated component (e.g., device readable medium 1980 can comprise multiple separate hard drives as well as multiple RAM modules).

Similarly, network node 1960 can be composed of multiple physically separate components (e.g., a NodeB component and an RNC component, or a BTS component and a BSC component, etc.), which can each have their own respective components. In certain scenarios in which network node 1960 comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components can be shared among several network nodes. For example, a single RNC can control multiple NodeB's. In such a scenario, each unique NodeB and RNC pair, can in some instances be considered a single separate network node. In some embodiments, network node 1960 can be configured to support multiple radio access technologies (RATs). In such embodiments, some components can be duplicated (e.g., separate device readable medium 1980 for the different RATs) and some components can be reused (e.g., the same antenna 1962 can be shared by the RATs). Network node 1960 can also include multiple sets of the various illustrated components for different wireless technologies integrated into network node 1960, such as, for example, GSM, WCDMA, LTE, NR, WiFi, or Bluetooth wireless technologies. These wireless technologies can be integrated into the same or different chip or set of chips and other components within network node 1960.

Processing circuitry 1970 can be configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being provided by a network node. These operations performed by processing circuitry 1970 can include processing information obtained by processing circuitry 1970 by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination.

Processing circuitry 1970 can comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node 1960 components, such as device readable medium 1980, network node 1960 functionality. For example, processing circuitry 1970 can execute instructions stored in device readable medium 1980 or in memory within processing circuitry 1970. Such functionality can include providing any of the various wireless features, functions, or benefits discussed herein. In some embodiments, processing circuitry 1970 can include a system on a chip (SOC).

In some embodiments, processing circuitry 1970 can include one or more of radio frequency (RF) transceiver circuitry 1972 and baseband processing circuitry 1974. In some embodiments, radio frequency (RF) transceiver circuitry 1972 and baseband processing circuitry 1974 can be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry 1972 and baseband processing circuitry 1974 can be on the same chip or set of chips, boards, or units

In certain embodiments, some or all of the functionality described herein as being provided by a network node, base station, eNB or other such network device can be performed by processing circuitry 1970 executing instructions stored on device readable medium 1980 or memory within processing circuitry 1970. In alternative embodiments, some or all of the functionality can be provided by processing circuitry 1970 without executing instructions stored on a separate or discrete device readable medium, such as in a hard-wired manner. In any of those embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry 1970 can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry 1970 alone or to other components of network node 1960, but are enjoyed by network node 1960 as a whole, and/or by end users and the wireless network generally.

Device readable medium 1980 can comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer-executable memory devices that store information, data, and/or instructions that can be used by processing circuitry 1970. Device readable medium 1980 can store any suitable instructions, data or information, including a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry 1970 and, utilized by network node 1960. Device readable medium 1980 can be used to store any calculations made by processing circuitry 1970 and/or any data received via interface 1990. In some embodiments, processing circuitry 1970 and device readable medium 1980 can be considered to be integrated.

Interface 1990 is used in the wired or wireless communication of signaling and/or data between network node 1960, network 1906, and/or WDs 1910. As illustrated, interface 1990 comprises port(s)/terminal(s) 1994 to send and receive data, for example to and from network 1906 over a wired connection. Interface 1990 also includes radio front end circuitry 1992 that can be coupled to, or in certain embodiments a part of, antenna 1962. Radio front end circuitry 1992 comprises filters 1998 and amplifiers 1996. Radio front end circuitry 1992 can be connected to antenna 1962 and processing circuitry 1970. Radio front end circuitry can be configured to condition signals communicated between antenna 1962 and processing circuitry 1970. Radio front end circuitry 1992 can receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry 1992 can convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1998 and/or amplifiers 1996. The radio signal can then be transmitted via antenna 1962. Similarly, when receiving data, antenna 1962 can collect radio signals which are then converted into digital data by radio front end circuitry 1992. The digital data can be passed to processing circuitry 1970. In other embodiments, the interface can comprise different components and/or different combinations of components.

In certain alternative embodiments, network node 1960 may not include separate radio front end circuitry 1992, instead, processing circuitry 1970 can comprise radio front end circuitry and can be connected to antenna 1962 without separate radio front end circuitry 1992. Similarly, in some embodiments, all or some of RF transceiver circuitry 1972 can be considered a part of interface 1990. In still other embodiments, interface 1990 can include one or more ports or terminals 1994, radio front end circuitry 1992, and RF transceiver circuitry 1972, as part of a radio unit (not shown), and interface 1990 can communicate with baseband processing circuitry 1974, which is part of a digital unit (not shown).

Antenna 1962 can include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. Antenna 1962 can be coupled to radio front end circuitry 1990 and can be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna 1962 can comprise one or more omni-directional, sector or panel antennas operable to transmit/receive radio signals between, for example, 2 GHz and 66 GHz. An omni-directional antenna can be used to transmit/receive radio signals in any direction, a sector antenna can be used to transmit/receive radio signals from devices within a particular area, and a panel antenna can be a line of sight antenna used to transmit/receive radio signals in a relatively straight line. In some instances, the use of more than one antenna can be referred to as MIMO. In certain embodiments, antenna 1962 can be separate from network node 1960 and can be connectable to network node 1960 through an interface or port.

Antenna 1962, interface 1990, and/or processing circuitry 1970 can be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by a network node. Any information, data and/or signals can be received from a wireless device, another network node and/or any other network equipment. Similarly, antenna 1962, interface 1990, and/or processing circuitry 1970 can be configured to perform any transmitting operations described herein as being performed by a network node. Any information, data and/or signals can be transmitted to a wireless device, another network node and/or any other network equipment.

Power circuitry 1987 can comprise, or be coupled to, power management circuitry and can be configured to supply the components of network node 1960 with power for performing the functionality described herein. Power circuitry 1987 can receive power from power source 1986. Power source 1986 and/or power circuitry 1987 can be configured to provide power to the various components of network node 1960 in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source 1986 can either be included in, or external to, power circuitry 1987 and/or network node 1960. For example, network node 1960 can be connectable to an external power source (e.g., an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry 1987. As a further example, power source 1986 can comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry 1987. The battery can provide backup power should the external power source fail. Other types of power sources, such as photovoltaic devices, can also be used.

Alternative embodiments of network node 1960 can include additional components beyond those shown in FIG. 19 that can be responsible for providing certain aspects of the network node's functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, network node 1960 can include user interface equipment to allow and/or facilitate input of information into network node 1960 and to allow and/or facilitate output of information from network node 1960. This can allow and/or facilitate a user to perform diagnostic, maintenance, repair, and other administrative functions for network node 1960.

In some embodiments, a wireless device (WD, e.g., WD 1910) can be configured to transmit and/or receive information without direct human interaction. For instance, a WD can be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the network. Examples of a WD include, but are not limited to, smart phones, mobile phones, cell phones, voice over IP (VoIP) phones, wireless local loop phones, desktop computers, personal digital assistants (PDAs), wireless cameras, gaming consoles or devices, music storage devices, playback appliances, wearable devices, wireless endpoints, mobile stations, tablets, laptops, laptop-embedded equipment (LEE), laptop-mounted equipment (LME), smart devices, wireless customer-premise equipment (CPE), mobile-type communication (MTC) devices, Internet-of-Things (IoT) devices, vehicle-mounted wireless terminal devices, etc.

A WD can support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-everything (V2X) and can in this case be referred to as a D2D communication device. As yet another specific example, in an Internet of Things (IoT) scenario, a WD can represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another WD and/or a network node. The WD can in this case be a machine-to-machine (M2M) device, which can in a 3GPP context be referred to as an MTC device. As one particular example, the WD can be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances (e.g., refrigerators, televisions, etc.) personal wearables (e.g., watches, fitness trackers, etc.). In other scenarios, a WD can represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation. A WD as described above can represent the endpoint of a wireless connection, in which case the device can be referred to as a wireless terminal. Furthermore, a WD as described above can be mobile, in which case it can also be referred to as a mobile device or a mobile terminal.

As illustrated, wireless device 1910 includes antenna 1911, interface 1914, processing circuitry 1920, device readable medium 1930, user interface equipment 1932, auxiliary equipment 1934, power source 1936 and power circuitry 1937. WD 1910 can include multiple sets of one or more of the illustrated components for different wireless technologies supported by WD 1910, such as, for example, GSM, WCDMA, LTE, NR, WiFi, WiMAX, or Bluetooth wireless technologies, just to mention a few. These wireless technologies can be integrated into the same or different chips or set of chips as other components within WD 1910.

Antenna 1911 can include one or more antennas or antenna arrays, configured to send and/or receive wireless signals, and is connected to interface 1914. In certain alternative embodiments, antenna 1911 can be separate from WD 1910 and be connectable to WD 1910 through an interface or port. Antenna 1911, interface 1914, and/or processing circuitry 1920 can be configured to perform any receiving or transmitting operations described herein as being performed by a WD. Any information, data and/or signals can be received from a network node and/or another WD. In some embodiments, radio front end circuitry and/or antenna 1911 can be considered an interface.

As illustrated, interface 1914 comprises radio front end circuitry 1912 and antenna 1911. Radio front end circuitry 1912 comprise one or more filters 1918 and amplifiers 1916. Radio front end circuitry 1914 is connected to antenna 1911 and processing circuitry 1920, and can be configured to condition signals communicated between antenna 1911 and processing circuitry 1920. Radio front end circuitry 1912 can be coupled to or a part of antenna 1911. In some embodiments, WD 1910 may not include separate radio front end circuitry 1912; rather, processing circuitry 1920 can comprise radio front end circuitry and can be connected to antenna 1911. Similarly, in some embodiments, some or all of RF transceiver circuitry 1922 can be considered a part of interface 1914. Radio front end circuitry 1912 can receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry 1912 can convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters 1918 and/or amplifiers 1916. The radio signal can then be transmitted via antenna 1911. Similarly, when receiving data, antenna 1911 can collect radio signals which are then converted into digital data by radio front end circuitry 1912. The digital data can be passed to processing circuitry 1920. In other embodiments, the interface can comprise different components and/or different combinations of components.

Processing circuitry 1920 can comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software, and/or encoded logic operable to provide, either alone or in conjunction with other WD 1910 components, such as device readable medium 1930, WD 1910 functionality. Such functionality can include providing any of the various wireless features or benefits discussed herein. For example, processing circuitry 1920 can execute instructions stored in device readable medium 1930 or in memory within processing circuitry 1920 to provide the functionality disclosed herein.

As illustrated, processing circuitry 1920 includes one or more of RF transceiver circuitry 1922, baseband processing circuitry 1924, and application processing circuitry 1926. In other embodiments, the processing circuitry can comprise different components and/or different combinations of components. In certain embodiments processing circuitry 1920 of WD 1910 can comprise a SOC. In some embodiments, RF transceiver circuitry 1922, baseband processing circuitry 1924, and application processing circuitry 1926 can be on separate chips or sets of chips. In alternative embodiments, part or all of baseband processing circuitry 1924 and application processing circuitry 1926 can be combined into one chip or set of chips, and RF transceiver circuitry 1922 can be on a separate chip or set of chips. In still alternative embodiments, part or all of RF transceiver circuitry 1922 and baseband processing circuitry 1924 can be on the same chip or set of chips, and application processing circuitry 1926 can be on a separate chip or set of chips. In yet other alternative embodiments, part or all of RF transceiver circuitry 1922, baseband processing circuitry 1924, and application processing circuitry 1926 can be combined in the same chip or set of chips. In some embodiments, RF transceiver circuitry 1922 can be a part of interface 1914. RF transceiver circuitry 1922 can condition RF signals for processing circuitry 1920.

In certain embodiments, some or all of the functionality described herein as being performed by a WD can be provided by processing circuitry 1920 executing instructions stored on device readable medium 1930, which in certain embodiments can be a computer-readable storage medium. In alternative embodiments, some or all of the functionality can be provided by processing circuitry 1920 without executing instructions stored on a separate or discrete device readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry 1920 can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry 1920 alone or to other components of WD 1910, but are enjoyed by WD 1910 as a whole, and/or by end users and the wireless network generally.

Processing circuitry 1920 can be configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being performed by a WD. These operations, as performed by processing circuitry 1920, can include processing information obtained by processing circuitry 1920 by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored by WD 1910, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination.

Device readable medium 1930 can be operable to store a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry 1920. Device readable medium 1930 can include computer memory (e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer executable memory devices that store information, data, and/or instructions that can be used by processing circuitry 1920. In some embodiments, processing circuitry 1920 and device readable medium 1930 can be considered to be integrated.

User interface equipment 1932 can include components that allow and/or facilitate a human user to interact with WD 1910. Such interaction can be of many forms, such as visual, audial, tactile, etc. User interface equipment 1932 can be operable to produce output to the user and to allow and/or facilitate the user to provide input to WD 1910. The type of interaction can vary depending on the type of user interface equipment 1932 installed in WD 1910. For example, if WD 1910 is a smart phone, the interaction can be via a touch screen; if WD 1910 is a smart meter, the interaction can be through a screen that provides usage (e.g., the number of gallons used) or a speaker that provides an audible alert (e.g., if smoke is detected). User interface equipment 1932 can include input interfaces, devices and circuits, and output interfaces, devices and circuits. User interface equipment 1932 can be configured to allow and/or facilitate input of information into WD 1910, and is connected to processing circuitry 1920 to allow and/or facilitate processing circuitry 1920 to process the input information. User interface equipment 1932 can include, for example, a microphone, a proximity or other sensor, keys/buttons, a touch display, one or more cameras, a USB port, or other input circuitry. User interface equipment 1932 is also configured to allow and/or facilitate output of information from WD 1910, and to allow and/or facilitate processing circuitry 1920 to output information from WD 1910. User interface equipment 1932 can include, for example, a speaker, a display, vibrating circuitry, a USB port, a headphone interface, or other output circuitry. Using one or more input and output interfaces, devices, and circuits, of user interface equipment 1932, WD 1910 can communicate with end users and/or the wireless network, and allow and/or facilitate them to benefit from the functionality described herein.

Auxiliary equipment 1934 is operable to provide more specific functionality which may not be generally performed by WDs. This can comprise specialized sensors for doing measurements for various purposes, interfaces for additional types of communication such as wired communications etc. The inclusion and type of components of auxiliary equipment 1934 can vary depending on the embodiment and/or scenario.

Power source 1936 can, in some embodiments, be in the form of a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic devices or power cells, can also be used. WD 1910 can further comprise power circuitry 1937 for delivering power from power source 1936 to the various parts of WD 1910 which need power from power source 1936 to carry out any functionality described or indicated herein. Power circuitry 1937 can in certain embodiments comprise power management circuitry. Power circuitry 1937 can additionally or alternatively be operable to receive power from an external power source; in which case WD 1910 can be connectable to the external power source (such as an electricity outlet) via input circuitry or an interface such as an electrical power cable. Power circuitry 1937 can also in certain embodiments be operable to deliver power from an external power source to power source 1936. This can be, for example, for the charging of power source 1936. Power circuitry 1937 can perform any converting or other modification to the power from power source 1936 to make it suitable for supply to the respective components of WD 1910.

FIG. 20 illustrates one embodiment of a UE in accordance with various aspects described herein. As used herein, a user equipment or UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE can represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE can represent a device that is not intended for sale to, or operation by, an end user but which can be associated with or operated for the benefit of a user (e.g., a smart power meter). UE 20200 can be any UE identified by the 3^(rd) Generation Partnership Project (3GPP), including a NB-IoT UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE. UE 2000, as illustrated in FIG. 20 , is one example of a WD configured for communication in accordance with one or more communication standards promulgated by the 3^(rd) Generation Partnership Project (3GPP), such as 3GPP's GSM, UMTS, LTE, and/or 5G standards. As mentioned previously, the term WD and UE can be used interchangeable. Accordingly, although FIG. 20 is a UE, the components discussed herein are equally applicable to a WD, and vice-versa.

In FIG. 20 , UE 2000 includes processing circuitry 2001 that is operatively coupled to input/output interface 2005, radio frequency (RF) interface 2009, network connection interface 2011, memory 2015 including random access memory (RAM) 2017, read-only memory (ROM) 2019, and storage medium 2021 or the like, communication subsystem 2031, power source 2033, and/or any other component, or any combination thereof. Storage medium 2021 includes operating system 2023, application program 2025, and data 2027. In other embodiments, storage medium 2021 can include other similar types of information. Certain UEs can utilize all of the components shown in FIG. 20 , or only a subset of the components. The level of integration between the components can vary from one UE to another UE. Further, certain UEs can contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc.

In FIG. 20 , processing circuitry 2001 can be configured to process computer instructions and data. Processing circuitry 2001 can be configured to implement any sequential state machine operative to execute machine instructions stored as machine-readable computer programs in the memory, such as one or more hardware-implemented state machines (e.g., in discrete logic, FPGA, ASIC, etc.); programmable logic together with appropriate firmware; one or more stored program, general-purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry 2001 can include two central processing units (CPUs). Data can be information in a form suitable for use by a computer.

In the depicted embodiment, input/output interface 2005 can be configured to provide a communication interface to an input device, output device, or input and output device. UE 2000 can be configured to use an output device via input/output interface 2005. An output device can use the same type of interface port as an input device. For example, a USB port can be used to provide input to and output from UE 2000. The output device can be a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. UE 2000 can be configured to use an input device via input/output interface 2005 to allow and/or facilitate a user to capture information into UE 2000. The input device can include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display can include a capacitive or resistive touch sensor to sense input from a user. A sensor can be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, another like sensor, or any combination thereof. For example, the input device can be an accelerometer, a magnetometer, a digital camera, a microphone, and an optical sensor.

In FIG. 20 , RF interface 2009 can be configured to provide a communication interface to RF components such as a transmitter, a receiver, and an antenna. Network connection interface 2011 can be configured to provide a communication interface to network 2043 a. Network 2043 a can encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 2043 a can comprise a Wi-Fi network. Network connection interface 2011 can be configured to include a receiver and a transmitter interface used to communicate with one or more other devices over a communication network according to one or more communication protocols, such as Ethernet, TCP/IP, SONET, ATM, or the like. Network connection interface 2011 can implement receiver and transmitter functionality appropriate to the communication network links (e.g., optical, electrical, and the like). The transmitter and receiver functions can share circuit components, software or firmware, or alternatively can be implemented separately.

RAM 2017 can be configured to interface via bus 2002 to processing circuitry 2001 to provide storage or caching of data or computer instructions during the execution of software programs such as the operating system, application programs, and device drivers. ROM 2019 can be configured to provide computer instructions or data to processing circuitry 2001. For example, ROM 2019 can be configured to store invariant low-level system code or data for basic system functions such as basic input and output (I/O), startup, or reception of keystrokes from a keyboard that are stored in a non-volatile memory. Storage medium 2021 can be configured to include memory such as RAM, ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, or flash drives. In one example, storage medium 2021 can be configured to include operating system 2023, application program 2025 such as a web browser application, a widget or gadget engine or another application, and data file 2027. Storage medium 2021 can store, for use by UE 2000, any of a variety of various operating systems or combinations of operating systems.

Storage medium 2021 can be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), floppy disk drive, flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a subscriber identity module or a removable user identity (SIM/RUIM) module, other memory, or any combination thereof. Storage medium 2021 can allow and/or facilitate UE 2000 to access computer-executable instructions, application programs or the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system can be tangibly embodied in storage medium 2021, which can comprise a device readable medium.

In FIG. 20 , processing circuitry 2001 can be configured to communicate with network 2043 b using communication subsystem 2031. Network 2043 a and network 2043 b can be the same network or networks or different network or networks. Communication subsystem 2031 can be configured to include one or more transceivers used to communicate with network 2043 b. For example, communication subsystem 2031 can be configured to include one or more transceivers used to communicate with one or more remote transceivers of another device capable of wireless communication such as another WD, UE, or base station of a radio access network (RAN) according to one or more communication protocols, such as IEEE 802.20, CDMA, WCDMA, GSM, LTE, UTRAN, WiMax, or the like. Each transceiver can include transmitter 2033 and/or receiver 2035 to implement transmitter or receiver functionality, respectively, appropriate to the RAN links (e.g., frequency allocations and the like). Further, transmitter 2033 and receiver 2035 of each transceiver can share circuit components, software or firmware, or alternatively can be implemented separately.

In the illustrated embodiment, the communication functions of communication subsystem 2031 can include data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. For example, communication subsystem 2031 can include cellular communication, Wi-Fi communication, Bluetooth communication, and GPS communication. Network 2043 b can encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network 2043 b can be a cellular network, a Wi-Fi network, and/or a near-field network. Power source 2013 can be configured to provide alternating current (AC) or direct current (DC) power to components of UE 2000.

The features, benefits and/or functions described herein can be implemented in one of the components of UE 2000 or partitioned across multiple components of UE 2000. Further, the features, benefits, and/or functions described herein can be implemented in any combination of hardware, software or firmware. In one example, communication subsystem 2031 can be configured to include any of the components described herein. Further, processing circuitry 2001 can be configured to communicate with any of such components over bus 2002. In another example, any of such components can be represented by program instructions stored in memory that when executed by processing circuitry 2001 perform the corresponding functions described herein. In another example, the functionality of any of such components can be partitioned between processing circuitry 2001 and communication subsystem 2031. In another example, the non-computationally intensive functions of any of such components can be implemented in software or firmware and the computationally intensive functions can be implemented in hardware.

FIG. 21 is a schematic block diagram illustrating a virtualization environment 2100 in which functions implemented by some embodiments can be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which can include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to a node (e.g., a virtualized base station or a virtualized radio access node) or to a device (e.g., a UE, a wireless device or any other type of communication device) or components thereof and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components (e.g., via one or more applications, components, functions, virtual machines or containers executing on one or more physical processing nodes in one or more networks).

In some embodiments, some or all of the functions described herein can be implemented as virtual components executed by one or more virtual machines implemented in one or more virtual environments 2100 hosted by one or more of hardware nodes 2130. Further, in embodiments in which the virtual node is not a radio access node or does not require radio connectivity (e.g., a core network node), then the network node can be entirely virtualized.

The functions can be implemented by one or more applications 2120 (which can alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) operative to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein. Applications 2120 are run in virtualization environment 2100 which provides hardware 2130 comprising processing circuitry 2160 and memory 2190. Memory 2190 contains instructions 2195 executable by processing circuitry 2160 whereby application 2120 is operative to provide one or more of the features, benefits, and/or functions disclosed herein.

Virtualization environment 2100, comprises general-purpose or special-purpose network hardware devices 2130 comprising a set of one or more processors or processing circuitry 2160, which can be commercial off-the-shelf (COTS) processors, dedicated Application Specific Integrated Circuits (ASICs), or any other type of processing circuitry including digital or analog hardware components or special purpose processors. Each hardware device can comprise memory 2190-1 which can be non-persistent memory for temporarily storing instructions 2195 or software executed by processing circuitry 2160. Each hardware device can comprise one or more network interface controllers (NICs) 2170, also known as network interface cards, which include physical network interface 2180. Each hardware device can also include non-transitory, persistent, machine-readable storage media 2190-2 having stored therein software 2195 and/or instructions executable by processing circuitry 2160. Software 2195 can include any type of software including software for instantiating one or more virtualization layers 2150 (also referred to as hypervisors), software to execute virtual machines 2140 as well as software allowing it to execute functions, features and/or benefits described in relation with some embodiments described herein.

Virtual machines 2140, comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and can be run by a corresponding virtualization layer 2150 or hypervisor. Different embodiments of the instance of virtual appliance 2120 can be implemented on one or more of virtual machines 2140, and the implementations can be made in different ways.

During operation, processing circuitry 2160 executes software 2195 to instantiate the hypervisor or virtualization layer 2150, which can sometimes be referred to as a virtual machine monitor (VMM). Virtualization layer 2150 can present a virtual operating platform that appears like networking hardware to virtual machine 2140.

As shown in FIG. 21 , hardware 2130 can be a standalone network node with generic or specific components. Hardware 2130 can comprise antenna 21225 and can implement some functions via virtualization. Alternatively, hardware 2130 can be part of a larger cluster of hardware (e.g., such as in a data center or customer premise equipment (CPE)) where many hardware nodes work together and are managed via management and orchestration (MANO) 21100, which, among others, oversees lifecycle management of applications 2120.

Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV can be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment.

In the context of NFV, virtual machine 2140 can be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of virtual machines 2140, and that part of hardware 2130 that executes that virtual machine, be it hardware dedicated to that virtual machine and/or hardware shared by that virtual machine with others of the virtual machines 2140, forms a separate virtual network elements (VNE).

Still in the context of NFV, Virtual Network Function (VNF) is responsible for handling specific network functions that run in one or more virtual machines 2140 on top of hardware networking infrastructure 2130 and corresponds to application 2120 in FIG. 21 .

In some embodiments, one or more radio units 21200 that each include one or more transmitters 21220 and one or more receivers 21210 can be coupled to one or more antennas 21225. Radio units 21200 can communicate directly with hardware nodes 2130 via one or more appropriate network interfaces and can be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station.

In some embodiments, some signaling can be performed using control system 21230 which can alternatively be used for communication between the hardware nodes 2130 and radio units 21200.

With reference to FIG. 22 , in accordance with an embodiment, a communication system includes telecommunication network 2210, such as a 3GPP-type cellular network, which comprises access network 2211, such as a radio access network, and core network 2214. Access network 2211 comprises a plurality of base stations 2212 a, 2212 b, 2212 c, such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 2213 a, 2213 b, 2213 c. Each base station 2212 a, 2212 b, 2212 c is connectable to core network 2214 over a wired or wireless connection 2215. A first UE 2291 located in coverage area 2213 c can be configured to wirelessly connect to, or be paged by, the corresponding base station 2212 c. A second UE 2292 in coverage area 2213 a is wirelessly connectable to the corresponding base station 2212 a. While a plurality of UEs 2291, 2292 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the

Telecommunication network 2210 is itself connected to host computer 2230, which can be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. Host computer 2230 can be under the ownership or control of a service provider, or can be operated by the service provider or on behalf of the service provider. Connections 2221 and 2222 between telecommunication network 2210 and host computer 2230 can extend directly from core network 2214 to host computer 2230 or can go via an optional intermediate network 2220. Intermediate network 2220 can be one of, or a combination of more than one of, a public, private or hosted network; intermediate network 2220, if any, can be a backbone network or the Internet; in particular, intermediate network 2220 can comprise two or more sub-networks (not shown).

The communication system of FIG. 22 as a whole enables connectivity between the connected UEs 2291, 2292 and host computer 2230. The connectivity can be described as an over-the-top (OTT) connection 2250. Host computer 2230 and the connected UEs 2291, 2292 are configured to communicate data and/or signaling via OTT connection 2250, using access network 2211, core network 2214, any intermediate network 2220 and possible further infrastructure (not shown) as intermediaries. OTT connection 2250 can be transparent in the sense that the participating communication devices through which OTT connection 2250 passes are unaware of routing of uplink and downlink communications. For example, base station 2212 may not or need not be informed about the past routing of an incoming downlink communication with data originating from host computer 2230 to be forwarded (e.g., handed over) to a connected UE 2291. Similarly, base station 2212 need not be aware of the future routing of an outgoing uplink communication originating from the UE 2291 towards the host computer 2230.

Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to FIG. 23 . In communication system 2300, host computer 2310 comprises hardware 2315 including communication interface 2316 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of communication system 2300. Host computer 2310 further comprises processing circuitry 2318, which can have storage and/or processing capabilities. In particular, processing circuitry 2318 can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Host computer 2310 further comprises software 2311, which is stored in or accessible by host computer 2310 and executable by processing circuitry 2318. Software 2311 includes host application 2312. Host application 2312 can be operable to provide a service to a remote user, such as UE 2330 connecting via OTT connection 2350 terminating at UE 2330 and host computer 2310. In providing the service to the remote user, host application 2312 can provide user data which is transmitted using OTT connection 2350.

Communication system 2300 can also include base station 2320 provided in a telecommunication system and comprising hardware 2325 enabling it to communicate with host computer 2310 and with UE 2330. Hardware 2325 can include communication interface 2326 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of communication system 2300, as well as radio interface 2327 for setting up and maintaining at least wireless connection 2370 with UE 2330 located in a coverage area (not shown in FIG. 23 ) served by base station 2320. Communication interface 2326 can be configured to facilitate connection 2360 to host computer 2310. Connection 2360 can be direct or it can pass through a core network (not shown in FIG. 23 ) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, hardware 2325 of base station 2320 can also include processing circuitry 2328, which can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Base station 2320 further has software 2321 stored internally or accessible via an external connection.

Communication system 2300 can also include UE 2330 whose hardware 2335 can include radio interface 2337 configured to set up and maintain wireless connection 2370 with a base station serving a coverage area in which UE 2330 is currently located. Hardware 2335 of UE 2330 can also include processing circuitry 2338, which can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. UE 2330 further comprises software 2331, which is stored in or accessible by UE 2330 and executable by processing circuitry 2338. Software 2331 includes client application 2332. Client application 2332 can be operable to provide a service to a human or non-human user via UE 2330, with the support of host computer 2310. In host computer 2310, an executing host application 2312 can communicate with the executing client application 2332 via OTT connection 2350 terminating at UE 2330 and host computer 2310. In providing the service to the user, client application 2332 can receive request data from host application 2312 and provide user data in response to the request data. OTT connection 2350 can transfer both the request data and the user data. Client application 2332 can interact with the user to generate the user data that it provides.

It is noted that host computer 2310, base station 2320 and UE 2330 illustrated in FIG. 23 can be similar or identical to host computer 2230, one of base stations 2212 a, 2212 b, 2212 c and one of UEs 2291, 2292 of FIG. 22 , respectively. This is to say, the inner workings of these entities can be as shown in FIG. 23 and independently, the surrounding network topology can be that of FIG. 22 .

In FIG. 23 , OTT connection 2350 has been drawn abstractly to illustrate the communication between host computer 2310 and UE 2330 via base station 2320, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure can determine the routing, which it can be configured to hide from UE 2330 or from the service provider operating host computer 2310, or both. While OTT connection 2350 is active, the network infrastructure can further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

Wireless connection 2370 between UE 2330 and base station 2320 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to UE 2330 using OTT connection 2350, in which wireless connection 2370 forms the last segment. More precisely, the exemplary embodiments disclosed herein can improve flexibility for the network to monitor end-to-end quality-of-service (QoS) of data flows, including their corresponding radio bearers, associated with data sessions between a user equipment (UE) and another entity, such as an OTT data application or service external to the 5G network. These and other advantages can facilitate more timely design, implementation, and deployment of 5G/NR solutions. Furthermore, such embodiments can facilitate flexible and timely control of data session QoS, which can lead to improvements in capacity, throughput, latency, etc. that are envisioned by 5G/NR and important for the growth of OTT services.

A measurement procedure can be provided for the purpose of monitoring data rate, latency and other network operational aspects on which the one or more embodiments improve. There can further be an optional network functionality for reconfiguring OTT connection 2350 between host computer 2310 and UE 2330, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring OTT connection 2350 can be implemented in software 2311 and hardware 2315 of host computer 2310 or in software 2331 and hardware 2335 of UE 2330, or both. In embodiments, sensors (not shown) can be deployed in or in association with communication devices through which OTT connection 2350 passes; the sensors can participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 2311, 2331 can compute or estimate the monitored quantities. The reconfiguring of OTT connection 2350 can include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect base station 2320, and it can be unknown or imperceptible to base station 2320. Such procedures and functionalities can be known and practiced in the art. In certain embodiments, measurements can involve proprietary UE signaling facilitating host computer 2310's measurements of throughput, propagation times, latency and the like. The measurements can be implemented in that software 2311 and 2331 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using OTT connection 2350 while it monitors propagation times, errors etc.

FIG. 24 is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which, in some exemplary embodiments, can be those described with reference to FIGS. 22 and 23 . For simplicity of the present disclosure, only drawing references to FIG. 24 will be included in this section. In step 2410, the host computer provides user data. In substep 2411 (which can be optional) of step 2410, the host computer provides the user data by executing a host application. In step 2420, the host computer initiates a transmission carrying the user data to the UE. In step 2430 (which can be optional), the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 2440 (which can also be optional), the UE executes a client application associated with the host application executed by the host computer.

FIG. 25 is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to FIGS. 22 and 23 . For simplicity of the present disclosure, only drawing references to FIG. 25 will be included in this section. In step 2510 of the method, the host computer provides user data. In an optional substep (not shown) the host computer provides the user data by executing a host application. In step 2520, the host computer initiates a transmission carrying the user data to the UE. The transmission can pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step 2530 (which can be optional), the UE receives the user data carried in the transmission.

FIG. 26 is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to FIGS. 22 and 23 . For simplicity of the present disclosure, only drawing references to FIG. 26 will be included in this section. In step 2610 (which can be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step 2620, the UE provides user data. In substep 2621 (which can be optional) of step 2620, the UE provides the user data by executing a client application. In substep 2611 (which can be optional) of step 2610, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application can further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in substep 2630 (which can be optional), transmission of the user data to the host computer. In step 2640 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

FIG. 27 is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to FIGS. 22 and 23 . For simplicity of the present disclosure, only drawing references to FIG. 27 will be included in this section. In step 2710 (which can be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step 2720 (which can be optional), the base station initiates transmission of the received user data to the host computer. In step 2730 (which can be optional), the host computer receives the user data carried in the transmission initiated by the base station.

The foregoing merely illustrates the principles of the disclosure. Various modifications and alterations to the described embodiments will be apparent to those skilled in the art in view of the teachings herein. It will thus be appreciated that those skilled in the art will be able to devise numerous systems, arrangements, and procedures that, although not explicitly shown or described herein, embody the principles of the disclosure and can be thus within the spirit and scope of the disclosure. Various exemplary embodiments can be used together with one another, as well as interchangeably therewith, as should be understood by those having ordinary skill in the art.

The term unit, as used herein, can have conventional meaning in the field of electronics, electrical devices and/or electronic devices and can include, for example, electrical and/or electronic circuitry, devices, modules, processors, memories, logic solid state and/or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and/or displaying functions, and so on, as such as those that are described herein.

Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processor (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as Read Only Memory (ROM), Random Access Memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure.

As described herein, device and/or apparatus can be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device or apparatus, instead of being hardware implemented, be implemented as a software module such as a computer program or a computer program product comprising executable software code portions for execution or being run on a processor. Furthermore, functionality of a device or apparatus can be implemented by any combination of hardware and software. A device or apparatus can also be regarded as an assembly of multiple devices and/or apparatuses, whether functionally in cooperation with or independently of each other. Moreover, devices and apparatuses can be implemented in a distributed fashion throughout a system, so long as the functionality of the device or apparatus is preserved. Such and similar principles are considered as known to a skilled person.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

In addition, certain terms used in the present disclosure, including the specification, drawings and exemplary embodiments thereof, can be used synonymously in certain instances, including, but not limited to, e.g., data and information. It should be understood that, while these words and/or other words that can be synonymous to one another, can be used synonymously herein, that there can be instances when such words can be intended to not be used synonymously. Further, to the extent that the prior art knowledge has not been explicitly incorporated by reference herein above, it is explicitly incorporated herein in its entirety. All publications referenced are incorporated herein by reference in their entireties.

Example embodiments of the techniques and apparatus described herein include, but are not limited to, the following enumerated examples:

-   1. A method for a network node to establish a connection with a user     equipment (UE) operating in dual connectivity (DC) with a primary     cell of a first radio access technology (RAT) served by a master     node (MN) and with a secondary cell of a second RAT served by a     secondary node (SN) of the serving cell, the method comprising:     -   receiving, from the UE, a re-establishment request message         comprising:         -   an indication of the UE's selection of a further cell served             by the network node for re-establishment as the primary cell             for the DC, wherein the further cell is of the second RAT;         -   a plurality of parameters associated with the SN; and         -   a message authentication code (MAC) calculated based on a             plurality of parameters associated with the MN;     -   based on the plurality of parameters, determining a first         identifier of the UE associated with the MN and an identifier of         the primary cell;     -   sending, to either the MN or the SN, a context request message         comprising the first UE identifier, the primary cell identifier,         the MAC, and a request for a UE context associated with the UE         identifier;     -   receiving, from either the MN or the SN, a context response         message comprising the UE context and a second identifier of the         UE; and     -   re-establishing the further cell as the primary cell for the UE         DC. -   2. The method of embodiment 1, further comprising sending, to the     UE, a connection re-establishment message indicating the further     cell as the primary cell for UE DC. -   3. The method of any of embodiments 1-2, wherein the first RAT is     New Radio (NR) and the second RAT is Long-Term Evolution Evolved     UTRA (LTE E-UTRA). -   4. The method of any of embodiments 1-2, wherein the second RAT is     New Radio (NR) and the first RAT is Long-Term Evolution Evolved UTRA     (LTE E-UTRA). -   5. A method performed by a user equipment (UE) operating in dual     connectivity (DC) with a primary cell of a first radio access     technology (RAT) served by a master node (MN) and with a secondary     cell of a second RAT served by a secondary node (SN), the method     comprising:     -   detecting a failure associated with the primary cell served by         the MN;     -   selecting a further cell for re-establishment as the primary         cell for DC;     -   calculating a message authentication code (MAC) for a         re-establishment request message based on a plurality of         parameters associated with the MN, wherein if the selected         further cell is of the second RAT, the calculating includes         converting one or more of the plurality of parameters into         respective formats associated with the first RAT; and     -   sending the re-establishment request message, including the         calculated MAC, to a network node serving the further cell. -   6. The method of embodiment 5, wherein the first RAT is New Radio     (NR) and the second RAT is Long-Term Evolution Evolved UTRA (LTE     E-UTRA). -   7. The method of embodiment 5, wherein the second RAT is New Radio     (NR) and the first RAT is Long-Term Evolution Evolved UTRA (LTE     E-UTRA). -   8. The method of any of embodiments 5-7, wherein the network node     serving the further cell is the SN. -   9. The method of any of embodiments 5-7, wherein the network node     serving the further cell is different than the SN. -   10. The method of any of embodiments 5-9, further comprising     receiving, from the network node, a connection re-establishment     message indicating the further cell as the primary cell. -   11. A network node configured to establish a connection with a user     equipment (UE) operating in dual connectivity (DC) with a primary     cell of a first radio access technology (RAT) served by a master     node (MN) and with a secondary cell of a second RAT served by a     secondary node (SN) of the serving cell, the network node     comprising:     -   a communication interface; and     -   processing circuitry operably coupled to the communication         interface and configured to perform any operations of any of         embodiments 1-4; and     -   power supply circuitry configured to supply power to the network         node. -   12. A user equipment (UE) configured to operate in dual     connectivity (DC) with a primary cell of a first radio access     technology (RAT) served by a master node (MN) and with a secondary     cell of a second RAT served by a secondary node (SN), the UE     comprising:     -   a communication interface; and     -   processing circuitry operably coupled to the communication         interface and configured to perform any operations of any of         embodiments 5-10; and     -   power supply circuitry configured to supply power to the UE. -   13. A communication system including a host computer comprising:     -   processing circuitry configured to provide user data; and     -   a communication interface configured to forward the user data to         a cellular network for transmission to a user equipment (UE),         wherein the cellular network comprises a base station having a         radio interface and processing circuitry, the base station's         processing circuitry configured to perform any of the operations         comprising embodiments 1-4. -   14. The communication system of the previous embodiment further     including the base station. -   15. The communication system of the previous two embodiments,     further including the UE, wherein the UE includes a radio interface     and processing circuitry configured to communicate with the base     station and cooperatively perform any of the operations comprising     embodiments 5-10. -   16. The communication system of the previous three embodiments,     wherein:     -   the processing circuitry of the host computer is configured to         execute a host application, thereby providing the user data; and     -   the UE's processing circuitry is further configured to execute a         client application associated with the host application. -   17. A method implemented in a communication system including a host     computer, a base station, and a User Equipment (UE), the method     comprising:     -   at the host computer, providing user data;     -   at the host computer, initiating a transmission carrying the         user data to the UE via a cellular network comprising the base         station; and     -   at the base station, performing operations corresponding to any         of embodiments 1-4. -   18. The method of the previous embodiment, further comprising, at     the base station, transmitting the user data. -   19. The method of the previous two embodiments, wherein the user     data is provided at the host computer by executing a host     application, the method further comprising, at the UE, executing a     client application associated with the host application. -   20. The method of the previous three embodiments, further     comprising, at the UE, performing operations corresponding to any of     embodiments 5-10. -   21. A communication system including a host computer comprising a     communication interface configured to receive user data originating     from a transmission from a User equipment (UE) to a base station,     the base station comprising a radio interface and processing     circuitry configured to communicate with the base station and     cooperatively perform operations of any of embodiments 1-4. -   22. The communication system of the previous embodiment further     including the base station. -   23. The communication system of the previous two embodiments,     further including the UE, wherein the UE includes a radio interface     and processing circuitry configured to communicate with the base     station and perform any of the operations comprising embodiments     5-10. -   24. The communication system of the previous three embodiments,     wherein:     -   the processing circuitry of the host computer is configured to         execute a host application; and     -   the UE is further configured to execute a client application         associated with the host application, thereby providing the user         data to be received by the host computer. 

The invention claimed is:
 1. A method for a target node, in a radio access network (RAN), to establish a connection with a user equipment (UE) operating in dual connectivity (DC) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN), and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN), the method comprising: receiving, from the UE, a re-establishment request message comprising: a plurality of parameters associated with the PSCell, a first message authentication code (MAC), and an indication of the UE's selection of a target cell served by the target node as a replacement for the PCell: the PCell utilizes utilizing a first radio access technology (RAT), and the PSCell and the target cell utilizing a second RAT different from the first RAT; verifying integrity of the re-establishment request message based on the first MAC; determining a full UE context for the UE based on: the plurality of parameters associated with the PSCell, and a successful verification of the integrity of the re-establishment request message; and establishing a connection with the UE based on the full UE context, whereby the target cell served by the target node will serve as a PCell for DC; and the determining the full UE context comprises: based on the plurality of parameters associated with the PSCell, determining that the target node is different than the SN; sending, to the SN, a context request message including the plurality of parameters associated with the PSCell; and receiving, from the MN, a context response message including the full UE context.
 2. The method of claim 1, wherein the MAC included in the re-establishment request message is based on a plurality of parameters associated with the PSCell and on an identifier of the target cell.
 3. The method of claim 2, wherein the plurality of parameters associated with the PSCell include an identifier of the PSCell, an identifier of the UE in relation to the PSCell, and integrity protection information associated with the SN.
 4. The method of claim 1, wherein determining the full UE context comprises: performing the following operations based on the plurality of parameters associated with the PSCell: determining that the target node is the same as the SN; and retrieving a UE context associated with the SN, wherein the UE context associated with the SN includes a first identifier of the UE in relation to the MN; sending, to the MN, a context request message including the first identifier of the UE in relation to the MN; and receiving, from the MN, a context response message including the full UE context.
 5. The method of claim 4, wherein: the UE context associated with the SN includes integrity protection information associated with the SN; and verifying the integrity of the re-establishment request message comprises: calculating a second MAC based on an identifier of the target cell, the plurality of parameters associated with the PSCell, and the integrity protection information associated with the SN; and comparing the first MAC and the second MAC to determine if there is a match between the first MAC and the second MAC, wherein a match indicates successful verification of the integrity.
 6. The method of claim 5, wherein the identifier of the target cell is included in the re-establishment request message.
 7. The method of claim 5, wherein the context request message is sent to the MN based on determining that there is a match between the first MAC and the second MAC.
 8. The method of claim 1, wherein verifying the integrity of the re-establishment request message comprises sending the first MAC in the context request message for verification by the SN.
 9. A network node, of a radio access network, RAN, configured to operate in dual connectivity towards a user equipment, UE together with a further network node in the RAN to establish a connection with a user equipment (UE) operating in dual connectivity (DC) with a master cell group (MCG) comprising a primary cell (PCell) served by a master node (MN), and with a secondary cell group (SCG) comprising a primary secondary cell (PSCell) served by a secondary node (SN), the network node comprising: interface circuitry operable to communicate with the UE and with at least the further network node in the RAN; and processing circuitry operably coupled to the interface circuitry, whereby the processing circuitry and the interface circuitry are configured to receive, from the UE, a re-establishment request message comprising: a plurality of parameters associated with the PSCell, a first message authentication code (MAC), and an indication of the UE's selection of a target cell served by a target node as a replacement for the PCell: the PCell utilizes a first radio access technology (RAT), and the PSCell and the target cell utilize a second RAT different from the first RAT; and verify integrity of the re-establishment request message based on the first MAC; determine a full UE context for the UE based on: the plurality of parameters associated with the PSCell, and a successful verification of the integrity of the re-establishment request message; establish a connection with the UE based on the full UE context, whereby the target cell served by the target node will serve as a PCell for DC; and the determining the full UE context comprises: based on the plurality of parameters associated with the PSCell, determining that the target node is different than the SN; sending, to the SN, a context request message including the plurality of parameters associated with the PSCell; and receiving, from the MN, a context response message including the full UE context.
 10. The network node of claim 9, wherein the MAC included in the re-establishment request message is based on a plurality of parameters associated with the PSCell and on an identifier of the target cell.
 11. The network node of claim 10, wherein the plurality of parameters associated with the PSCell include an identifier of the PSCell, an identifier of the UE in relation to the PSCell, and integrity protection information associated with the SN.
 12. The network node of claim 9, wherein determining the full UE context comprises: performing the following operations based on the plurality of parameters associated with the PSCell: determining that the target node is the same as the SN; and retrieving a UE context associated with the SN, wherein the UE context associated with the SN includes a first identifier of the UE in relation to the MN; sending, to the MN, a context request message including the first identifier of the UE in relation to the MN; and receiving, from the MN, a context response message including the full UE context.
 13. The network node of claim 12, wherein: the UE context associated with the SN includes integrity protection information associated with the SN; and verifying the integrity of the re-establishment request message comprises: calculating a second MAC based on an identifier of the target cell, the plurality of parameters associated with the PSCell, and the integrity protection information associated with the SN; and comparing the first MAC and the second MAC to determine if there is a match between the first MAC and the second MAC, wherein a match indicates successful verification of the integrity.
 14. The network node of claim 13, wherein the identifier of the target cell is included in the re-establishment request message.
 15. The network node of claim 13, wherein the context request message is sent to the MN based on determining that there is a match between the first MAC and the second MAC.
 16. The network node of claim 9, wherein verifying the integrity of the re-establishment request message comprises sending the first MAC in the context request message for verification by the SN. 